Study on species composition and some biological characteristics of eleotridae living in the bassac river

MINISTRY OF EDUCATION AND TRAINING CANTHO UNIVERSITY SUMMARY OF PhD THESIS Major in Aquaculture Identification code: 62620301 VO THANH TOAN STUDY ON SPECIES COMPOSITION AND SOME BIOLOGICAL CHARACTERISTICS OF ELEOTRIDAE LIVING IN THE BASSAC RIVER Can Tho, 2016 A THIS STUDY HAS BEEN COMPLETED AT CAN THO UNIVERSITY Supervisors: Assoc Dr Tran Dac Dinh Dr Ha Phuoc Hung The thesis was confirmed at the defence committee of Can Tho University Venue: ………………………………………………………………… Time: ……………………………………………………………… … Reviewer 1: Reviewer 2: Reviewer 3: This thesis is available at: Learning Resource Centre, Can Tho University Vietnam National Library B CHAPTER 1: INTRODUCTION 1.1 General introduction Goby has been the largest fish group with about 220 genera and 1,875 species belonging to five families (Eleotridae, Gobiidae, Periophthalmidae, Apocrypteidae and Gobioididae) (Healey, 1971) Among them, Eleotridae has comprised 31 genera and 178 species (Froese and Pauly, 2014) In the Mekong river basin, there have been 34 genera and 101 species belonging to five families (Rainboth, 1996) These five fish families are also found in Vietnam, and Eleotridae consist of three genera and seven species (Mai Dinh Yen, 1992; Nguyen Huu Phung, 1997; and Nguyen Nhat Thi, 2000) Similarily, Tran Dac Dinh et al (2013) showed that there were seven species in Mekong Delta (MD) including: Eleotris melanosoma (Bleeker, 1853); Butis butis (Hamilton, 1822); Butis humeralis (Valenciennes, 1837); Oxyeleotris marmorata (Bleeker, 1852); Oxyeleotris urophthalmus (Bleeker, 1853); Bostrychus scalaris (Larson, 2008) and Butis koilomatodon (Bleeker, 1849) Some species had economic values such as O marmorata, O urophthalmus and E melanosoma usually living in inland areas and estuaries (Murdy, 1989), and in tropical and subtropical areas (Chotkowski et al., 1999) Many spcecies came there for spawning and completing lifecycle (Blaber et al., 2000) Species of O marmorata was raised and catched at fishing areas along in Bassac river, in which species of O urophthalmus and E melanosoma had economic values because of meat delicious and highly productive (MOFI, 1996) However, they were not been much studying and only some studies were done on species of diversity and their biological characteristics Presently, knowledge of those species, the abundance of species of Eleotridae living in Mekong river basin, as well as nutritional characteristics and reproductive biology of O urophthalmus and E melanosoma were not much announced although they were among of the groups with high economic values in the MD So, study on species composition of Eleotridae and biological characteristics of gobies were very essential 1.2 General objective of study The overal objective aims to determine of species, abundance of Eleotridae and biological characteristics of gobies living in Bassac river in the contribution to the protection of aquatic resources products and providing the basis for researching on artificial breeding of some gobies having economic value in the future 1.3 The significance of the thesis The results of this thesis to supplement scientific data about the species of Eleotridae and biological characteristics of gobies living in Bassac river These results were used as resources for teaching and scientific researching in order to manage, restore and regenerate fisheries resources in general and particular groups of goby 1.4 The significant results i) Survey resulted some ecological parameters showed that the salinity was related to the living in gobies of Eleotridae, especially species of E melanosoma and B butis Catch per unit effort (CPUE) of these species had seasonal fluctuations and depended on the diversity of aquatic species, flow speed and water depth ii) There were five species of Eleotridae living in Bassac river, in which species of E melanosoma, O urophthalmus and O marmorata appeared more in upstream and middle while B Butis appeared in the middle and downstream, especially species of Butis humeralis appeared only in the downstream However, catched by trawl net showed that species of E melanosoma appeared in the upstream and middle, while B butis just appeared in the downstream CPUE of E melanosoma was more B Butis The abundance in rainy season was more in dry season iii) Species of E melanosoma and O urophthalmus had morphological gastrointestinal tract matching animal feeding Although there were four groups of food appeared in nutritional spectrum, but only three groups were considered as the favorite food for these species (crustaceans, molluscs and fingerling) The ratio of kinds of food also changed with increasing the total length and width of their mouth iv) The value of gonadosomatic index (GSI) of E melanosoma and O urophthalmus was high from May to October, while the hepatosomatic index (HSI) was low in July; conditional factor (CF) was highest in April and November showing that reproductive seasonality of this two species was along from May to October and concentrated from May to July The results also showed that the fecundity species of E melanosoma ranged from 49 to 930 eggs/g of female and higher than O urophthalmus (from 44 to 477 eggs/g of female) Absolute fecundity of E melanosoma from 2,981-19,520 eggs/ female and O urophthalmus from 1,290-9,999 eggs/female Length of maturity (Lm) of E melanosoma was 8.62 cm (in male) and 7.79 cm (in female); while Lm of O urophthalmus was 11.36 cm (in male) and 7.96 cm (in female) CHAPTER 3: MATERIALS AND METHODS 3.1 Time and site study This study was carried out from August 2012 to December 2014 The study sites were in the upstream (An Giang province), middle (Can Tho city) and downstream (Soc Trang province) in Bassac river (Figure 2.1) Figure 2.1: Diagram sampling areas in Bassac river (www.maps.google.com, accessed on 05/06/2012) 3.2 Materials and methods of study 3.2.1 Study 1: Identify some ecological parameters (temperature, pH, salinity, water flow, water depth, phytoplankton, zooplankton and zoobenthos) in Bassac river Identifying some ecological parameters in the target areas was performed from August 2012 to June 2013 at the same time and place of gobies that collected by trawl net in the upstream, middle and downstream in Bassac river Each area collected five points, sampling cycle two months, in which: a) Value of pH, temperature and salinity of the water were determined by the used of specialized equipment: pH meter, thermometer, refractometers at the field (Figure 2.2) b) Water flow was determined by the flowmeter (23090; Paul and Sally, 1977): Water flow (km/h)=distance measurement (km)/measurement time (hours); in which: (i) distance measurement=(number of rotor ring turned rotor x coefficient)/999999; and (ii) coefficient for flowmeter rotor (23090)=26,873 (Paul and Sally, 1977) c) The depth of water in the survey was measured in the field with a water depth measurement device (model PS-7FL Hondex) (Figure 2.2) Device of water depth measurement Device of refractometers Thermometer and GPS pH meter Figure 2.2: Some of devices used to collection of ecological parameters d) Species composition of phytoplankton, zooplankton and zoobenthos by phytoplankton net (mesh size of 30 micrometers), zooplankton net (mesh size 60 micrometers) and bottom Petersen (0.028 m2) combined with grating (500 micrometers), was collected at 15 points in three areas on Bassac river After collecting the sample in 110 ml plastic bottle with formaline fixed concentration of 2-8% (Petersen, 1990), phytoplankton samples were formaline fixed within 2%, zooplankton 4% and zoobenthos 8% Then they were analyzed by microscope objective lens in observing E10 at laboratories, Colledge of aquaculture and fisheries, Can Tho university + Determining the species composition of phytoplankton, zooplankton and zoobenthos was based on Shirota (1966), Duong Duc Tien and Vo Hanh (1997), and Carmelo et al (1996) + Determining the density of phytoplanktons, zooplanktons and zoobenthos was based on Boyd and Tucker (1992)  Density of phytoplanktons: X (ind./L) = (T*1.000*Vcondensed *103)/(A*N*Vsample) In which: T: Count the number of phytoplankton in each sector Vcondensed: Volume of condensed sample A: Area of one cell of sedgewick rafter cell S50 N: Number of cell of sedgewick rafter cell S50 Vsample: Volume of sample collection by phytoplankton net  Density of zooplankton: X (ind./m3) = (T*1.000*Vcondensed*106)/(A*N*Vsample) In which: T: Count the number of phytoplankton in each sector Vcondensed: Volume of condensed sample A: Area of one cell of sedgewick rafter cell S50 N: Number of cell of sedgewick rafter cell S50 Vsample: Volume of sample collection by phytoplankton net  Density of zoobenthos: D (ind./m2) = X/(N*d) In which: X: Count the number of zoobenthos in each sector N: Number of collection by zoobenthos Petersen D: Area of mouth zoobenthos Petersen (d=0.028 m2) 3.2.2 Study 2: Determine species of Eleotridae and abundance (CPUE) of gobies living in Bassac river Samples were collected by fishing, gillnet, trawl and directed collection of fishermen from fishing activities in study sites include the type of fishing such as bottom nets, fishing, put swamps nets, rubs and trawl Fish samples kept with ice and analyzed at the laboratory of fisheries resources, Can Tho university These indicators of morphological analyzed consists of: + Rate of standard length (cm) / head length (cm) + Rate of standard length (cm) / body height (cm); + Rate of head length (cm) / distance of between eyes(cm); + Rate of head length (cm) / snout length (cm); + Rate of edges length (cm) / height edges (cm); + Rate of body height (cm) / height edges (cm) Table 2.1: Number of sample to determine of morphological criteria of Eleotridae Unit: individual/species Eleotris Oxyeleotris Oxyeleotris Species Butis butis Butis humeralis melanosoma urophthalmus marmorata Number 45 50 36 41 54 The classification system in this study weas identified from level of family (Eleotridae) according to Lindberg (1971) (cited by Kanayama, 1991), the species level was mainly based on Smith (1991) Also, refer to the documents classified by the authors as: Cuvier and Valenciennes (18281848), Cantor (1848) (cited by Manilo and Bogorodsky, 2003), Taki (1974), Vuong Di Khang (1962) Three genus of Eleotridae were determined according to the following classification keys: 1.a- Skeletal gill covers front edge after one spiky toward to front … Eleotris 2.a- Thin scalp, the forehead between the eyes, skull clearly emerged It was covered by scales comb The lateral line along was 26-30 Butis 2.b- Thick scalp, skull covered Head and body covered the front of circular scales, flakes coated part after brush The lateral line along was 60-90 …………………………………………………… … ………… Oxyeleotris In this study, refer to the documentation of Mai Dinh Yen (1992), Truong Thu Khoa and Tran Thi Thu Huong (1993), Nguyen Nhat Thi (2000), Tran Dac Dinh et al (2013), Froese and Pauly (2014) to identify of gobies Determining the extent of relative abundance (CPUE) of Eleotridae was collected by trawl net with technical parameters: width at 4.5 m, height at 0.5 m, mesh size in the mouth and body at 25 mm, in refuge at15 mm, with cycle sampling in two months Location of sampling points in Bassac river on tributaries river (from the main river enters km, was located along the main river) started from upstream and downstream in the area of An Giang, Can Tho and Soc Trang; each area collected five points, three points earned in main river and tributaries at two collection points, location of points earned was determined by GPS (Global Positional System) A) Pelvic fins separately B) No lateral C) Two separate dorsal fins, include hard rays and soft rays D) Films bring discontinuous Figure 2.3: Some of major morphological characteristics of goby (Tran Dac Dinh at al., 2013) 3.2.3 Study 3: Study on nutritional characteristic of Eleotris melanosoma and Oxyeleotris urophthalmus Gobies samples were collected from June 2013 to May 2014, sampling cycle was once for two months at different size groups Each group collected at least 30 individuals per species (Table 3.2) Table 3.2: Number of samples analyzed nutritional spectrum of E melanosoma and O urophthalmus Unit: individual/species/month Rainy season (2013) Dry season (2014) Species Total June August October January March May E melanosoma 53 56 61 45 49 38 302 O urophthalmus 59 40 42 42 36 34 253 Gobies samples were fixed in formaline fluid with concentrations of 10%, then brought to the laboratory of aquatic resources fisheries, Can Tho University to analyze Method of determining feeding habits of goby based on morphological and structure of the digestive organs (shaped teeth, mouth, combs bearing, intestine length and types of food in the digestive tract) Food was removed from the gastrointestinal tract to liter of distilled water, shake well and take 100 ml continuing shake, then take ml for counting chamber (sedgewick rafter cell S50) and put on the microscope observation, analyzed by the method of frequency of occurrence (Hynes, 1950) and methods of weigth (Pillary, 1952) 2.2.3.1 Method of determined the morphological and structure of digestive organs Samples of E melanosoma and O urophthalmus obtained from Table 3.2 were analyzed identifying indicators: the width of mouth, length and body length of their intestine (Pravdin, 1973) To determine their feeding habits based on the correlation between the length of intestines and body length of gobies (relative length of the gut-RLG) RLG was calculated according to Al-Hussaini (1949): RLG=length intestine (cm)/ body length (cm) (RLG1: herbivorous) 2.2.3.2 Method of determining the nutritional spectrum + Methods of frequency of occurrence: The number of goby stomach presence of every type of food was calculated The percentage (%) of total number in stomach was observed, according to classified documents about the animal and aquatic plants of Shirota (1966), Duong Tien Duc and Vo Hanh (1997) and Carmelo et al (1996) + Method of weight: Most species of Eleotridae food ingredients of animal origin with a large weigth, so this study method was used in conjunction with the weigth and frequency of occurrence method to determine the food spectrum of E melanosoma and O urophthalmus in two steps: (i) use of electronic scales (3 decimal places) of the total mass balance of each type of food in the stomach of fish; and (ii) the weigth of each type of food to be converted into a percentage (%) of the total weigth of each food in stomach 3.2.4 Study 4: Study on reproductive biology characteristic of Eleotris melanosoma and Oxyeleotris urophthalmus Samples were collected from August 2012 to July 2013 and sampling cycle was once a month The analysis criteria includes: (i) Stages of sexual maturity: based on six steps sexual maturity recommended by Nikolsky (1963) and combined with histological methods of Drury & Wallington (1980) and Kiernan (1990) (ii) Rate of male and female: observed morphological characteristics and of gobies gonads to determine gender (iii) Gonadosomatic index (GSI): defined for each month, GSI (%)=(GW/BW)*100 (GW: weigth of fish gonad; BW: body weight) (iv) Hepatosomatic index (HSI) was also determined for each month HSI(%)=(LW/(BW)*100 (LW: liver weigth; BW: body weight of fish) (v) Correlation of length-weight, condition factor (CF): determining to the correlation between the length-weight based on Huxley (1924): W=a*Lb (W: total weight; L: total length; a and b: coefficients) Condition coefficient (CF) was determined: CF=W/Lb (W: body weight; L: total length; b: coefficient was determined based on the equation: W=a*Lb) (vi) Breeding season of them was determined basing on the result of determining stage of sexual maturity, GSI, HSI and CF (vii) Fecundity: determined basing on weigth of ovary, and representative sample of eggs was taken at three positions (beginning, middle and end of ovary) Absolute fecundity identified: PF=(n*G)/G (G: weigth of ovary (g); g: total body weight (g); n: number of representative samples of eggs (egg) Relative fecundity identified: RF=PF/BW (PF: absolute fecundity; BW: body weight) (Banegal, 1967) (viii) Mature length (Lm): the maturity length at which 50% of the total number of individuals in populations grow to maturity stage (stage III) (King, 1995) Curvature of P is expressed through the equation: ln [(1P)/P] = r*r*Lm-L, curve of this equation with linear (y=ax+b), original coefficient a=-r and launched the original b=r*Lm, using regression methods will determine Lm= -b/a and in this study was determined by software Stat 8.0 CHAPTER 4: RESULTS AND DISCUSSION 4.1 Identify ecological parameters (temperature, pH, salinity, water flow, depth, phytoplankton, zooplankton, zoobenthos) in Bassac river 4.1.1 Physical indicators (pH, temperature, salinity) Results showed that the pH value was little changed through six times survey (7.6-8.1), temperature from 29.1-30.9oC, salinity in the downstream appeared only in February, June and December, salinity in rainy season from to 7.6 ‰ and fluctuate less than the dry season (2-10.8‰) Results also showed that pH and temperature fluctuates seasonally (Figure 4.1) According to Cees et al (1995), some gobies living in salinity up to 25‰, but they lived in various types of water basins with different salinity, and they lived in an environment with temperature fluctuating large (28.731.9oC) even to 36.8oC 8.5 32 Rainy season Dry season Temperature (oC) Value of pH 31 8.0 7.5 30 Upstream Middle Surveyed areas Downstream Rainy season Dry season 29 28 27 7.0 Dry season Salinity (%o) Rainy season Upstream Middle Surveyed areas Downstream Upstream Middle Downstream Surveyed areas Figure 4.1: Fluctuations of pH, temperature and salinity in three areas surveyed 4.1.2 Water flow and water depth Water flow had many variations (0.1-1.3 km/hour); the locations of water Density of phytoplanktons in the upstream and downstream higher middle (Table 4.1) In the upstream highest in dry season (28,545±20,190 ind./L), euglenophyta was lowest (1,646±720 ind./L), highest in the middle of chlorophyta (5,333±3,479 ind./L) and lowest of euglenophyta (1,633±809 ind./L), highest in downstream (25, 59±28,583 ind./L) and lowest was cyanophyta (86±33 ind./L) and density of bacillariophyta highest in the upstream and downstream, lowest in the middle Table 4.1: The average density of phytoplanktons in three areas in Bassac river Area Upstream Middle Downstream Season Dry season Rainy season Dry season Rainy season Dry season Rainy season Bacillariophyta 28,545±20,190 10,294±2,186 4,586±1,017 6,986±3,060 25,759±28,583 2,239±862 Unit: individual/Liter Cyanophyta Chlorophyta 9,321±5,581 4,471±2,260 20,761±16,484 7,026±9,685 2,036±680 5,333±3,479 4,921±2,772 5,324±3,452 2,730±3,030 86±33 Euglenophyta 1,646±720 2,894±1,971 1,633±809 3,703±2,067 0 4.1.3.2 Zooplankton: Structure of zooplankton species occured in three areas, rotifera appeared total 111 species and 53 genus; in which protozoa has 51.4%, rotifer has 25.2%, copepoda has 18.9 and cladocera has 3.6% However, veliger (class of bivalvia larvae) appeared very few (0.9%) in the upstream and middle (Figure 4.5) This results was similar to Duong Tri Dung and Nguyen Hoang Oanh (2011), zooplankton species in the middle (canal Cai Khe) has 79 species and 54 species, in which rotifer was highest; however, this results higher of Ngo Duc Chan (2010) in the downstream has 48 species Veliger (0,9%) Copepoda (18,9%) Cladocera (3,6%) Rotifera (25,2%) Protozoa (51,4%) Figure 4.5: Structure of zooplanktons in the three areas surveyed 40 40 Dry season 25 20 15 10 35 Rainy season Dry season 30 25 20 15 10 Rainy season 35 Dry season 30 25 20 15 10 Protozoa Rotifera Cladocera Copepoda Veliger Frequency of occurrence (ind./season) 40 Rainy season 30 Frequency of occuurence (idn./season) Frequency of occurrence (ind./season) 35 Protozoa Rotifera Cladocera Copepoda Veliger Protozoa Rotifera Cladocera Copepoda Veliger Upstream Middle Downstream Figure 4.6: Frequency of occurrence of zooplanktons in three areas surveyed Density of zooplanktons in rainy season was higher in dry season, the 10 lowest in the middle and highest in downstream (Table 4.2) In which, density of Cladocera in the upstream highest (3,793±3,760 individuals/m3), Copepods in upstream lowest (1,037±361 individual/m3), density larval of Nauplius highest in the middle (2,741±1,935 individual/m3), while density of Protozoa was lowest in the middle (696±630 individual/m3), and density of Protozoa highest in downstream (35,408±38,256 individual/m3) Table 4.2: The average density of zooplanktons in three areas in Bassac river Unit: individual/m3 Area Upstream Middle Downstream Season Dry season Rainy season Dry season Rainy season Dry season Rainy season Protozoa 1,334±1,218 696±630 493±237 956±656 13,935±14,391 35,408±38,256 Rotifera 1,111±868 2,822±2,437 492±240 2,185±1,022 2,796±1,881 7,058±6,204 Cladocera 3,259±3,532 3,793±3,760 1,137±376 637±342 178±308 894±1,344 Copepoda 1,037±361 3,437±3,879 696±333 815±334 537±465 3,081±2,543 Nauplius 1,518±525 2,741±1,935 1,222±446 2,274±1,344 4,702±3,500 9,584±10,147 3.1.3.3 Zoobenthos: There were 73 species (upstream: 17 species, middle: 23 species, downstream: 33 species) with classes: Gastropoda, Bivalvia, Crustacea, Insecta, oligochaeta and Polychaeta In which, there were 12 species of Gastropoda highest (36%), Bivalvia species (24%), Oligochaeta species (12%), Crustacea species (12%), Polychaeta species (9%), Insecta species (6 ,%) This result was higher than the downstream (16 species) (Vu Ngoc Ut and Duong Thi Hoang Oanh, 2013) Crustacea (12%) Insecta (6%) Oligochaeta (12%) Bivalvia (24%) Polychaeta (9%) Gastropoda (36%) Rainy season Dry season Frequency of occurrence (ind.season) Frequency of occurrence (ind.season) Rainy season Dry season 1 Oligochaeta Polychaeta Gastropoda Bivalvia Crustacea Insecta Rainy season Dry season 0 Frequency of occurrence (ind.season) Figure 4.7: Structure of zoobenthos in the three areas surveyed Oligochaeta Polychaeta Gastropoda Bivalvia Crustacea Insecta Oligochaeta Polychaeta Gastropoda Bivalvia Crustacea Insecta Upstream Middle Downstream Figure 4.8: Frequency of occurrence of zoobenthos in three areas surveyed Density of zoobenthos in rainy season was higher compared to dry season In which, in the upstream and middle higher downstream (Table 4.3) In the upstream Oligochaeta has the highest density (82±57 ind./m2) and lowest was Gastropoda (7±1 ind./m2); in the middle density of Bivalvia highest (58±17 ind./m2) and lowest was Insecta (1±1 ind./m2), while downstream 11 density of Bivalvia has the highest (60±85 ind./m2) and lowest has Crustacea (8±6 ind./m2), Insecta and Oligochaeta does not appear Table 4.3: The average density of zoobenthos in three areas in Bassac river Unir: individual/m2 Area Upstream Middle Downstream Season Dry season Rainy season Dry season Rainy season Dry season Rainy season Oligochaeta Polychaeta Gastropoda Bivalvia Crustacea Insecta 25±7 82±57 16±11 38±4 0 15±14 23±4 18±14 55±3 30±22 12±14 63±43 7±1 28±17 24±6 12±15 21±30 83±19 11±10 55±41 58±17 60±85 53±34 50±30 16±20 15±15 50±39 8±6 17±26 55±17 8±5 9±9 1±1 6±13 4.2 Study on species of Eleotridae and abundance (CPUE) some of gobies in Bassac river 4.2.1 List of species (Eleotridae) There were five species appeared included: Eleotris melanosoma, Oxyeleotris urophthalmus, Oxyeleotris marmorata, Butis humeralis and Butis butis In which, species of B humeralis appeared only in areas downstream and species of B Butis appeared in the upstream and downstream; however E melanosoma, O urophthalmus and O marmorata occured in the upstream, middle and downstream in Bassac river (Table 4.4) Table 4.4: Distribution species of Eleotridae in Bassac river No Scientific name Eleotris melanosoma Bleeker, 1853 Oxyeleotris urophthalmus (Bleeker, 1851) Oxyeleotris marmorata (Bleeker, 1852) Butis butis (Hamilton, 1822) Butis humeralis (Valenciennes, 1837) Upstream Middle Downstream ++ + + ++ ++ + + ++ ++ + + + (+): Number of species appear less ( 0.05) The relative length of the gut of E melanosoma was also identified in three size groups (from 0.68 to 0.71) (Table 4.9) According to Nikolsky (1963), the species of fish were feeding the animals will be treated Li/Ls≤1, omnivorous fish with Li/Ls=1-3 and herbivorous fish when Li/Ls≥3, this results showed the feeding of E melanosoma was animals Table 4.9: Index of Lt, Li, RLG of Eleotris melanosoma in three sizes Targets Lt Li Li/Lt (RLG) Total length of fish (Lt, cm) Lt=2,5-5,0 Lt=5,1-7,0 4.57±0.52 6.00±0.51 3.10±0.62 4.29±0.60 0.439±0.171 0.614±0.134 Lt=7,1-9,0 67.62±0.48 5.39±0.58 0.666±0.137 Lt: Total length (cm); Li: Length of the gut (cm) O urophthalmus had a wide mouth, upper, mouth downward, almost to the mouth cavity, no mucus, characteristic stretching and feeding fish group large size Distributed on both sides of the tooth jaw, palate and pharynx, teeth a lot, and most had sharp dog teeth grow in many types of goods in the two upper and lower jaws Gill rakers were composed by three double bows bearing, each bearing with one double supply goods bearing combs (9-12 carries comb) located in the oropharyngeal cavity, white roses, piece, sir, forming a line spiky form, located on the same network hardware and instruction on oropharyngeal cavity The esophagus was located next 15 oropharyngeal cavity, that brings food to the stomach Tubular esophagus, small and short, present in many folds, which showed high resilience is carnivorous fish species Fish stomach esophagus is followed, in sinus introspection and feed storage function, providing enzymes involved in digesting food, bag-shaped, large, thick-walled, present in many folds can expand and accommodate large-sized prey Short gastric, Y-shaped, thickwalled, many folds create high elasticity and can accommodate large food The results showed that oral widths differ in three size groups, in groups of individuals with a total length (Lt) from 4.0 to 6.5 cm width mouth of O urophthalmus was 0.864±0.116 cm, in Lt=6.6 to 9.0 cm width mouth of O urophthalmus was 0.637±0.137 cm, in size from 9.1 to 12 cm width mouth was 0.231±1.078 cm and also showed that this species likely food choices and changes by an increase in the width of the mouth (Table 4:10) Table 4.10: The width of the mouth of O urophthalmus in three different sizes Group Total length (Lt, cm) Width of the mouth (cm) 4.0-6.5 0.464±0.116a 6.6-9.0 0.637±0.137b 9.1-12.0 1.078±0.231c Number of samples 27 71 155 The average value of a column with the same characters, the difference was not statistically significant (P> 0.05) The RLG of O urophthalmus was also analyzed in total length from to 12 cm and RLG was defined as less than 1, ranged from 0.63±0.12 to 0.74±0.15 (Table 4:11) Table 4.11: Index of Lt, Li, RLG of O urophthalmus in three sizes Total length of fish (Lt, cm) Targets Lt=4.0-6.5 Lt=6.6-9.0 Lt 5.85±0.58 8.04±0.75 Li 3.65±0.67 5.24±1.05 Li/Lt (RLG) 0.63±0.12 0.65±0.11 Lt: Total length (cm); Li: Length of the gut (cm) Lt=9.1-12.5 9.95±0.64 7.29±1.40 0.74±0.15 4.3.2 Nutritional spectrum of E melanosoma and O urophthalmus 4.3.2.1 Indegredient of food acording to the frequency method Indegredient of food of E melanosoma including: crustaceans, molluscs, small fish and other food (phytoplankton and zooplankton), in which molluscs with 19.57%, crustaceans (8.70%) and juveniles (2,20%), while other foods have a very high rate of 69.57% (Table 4.12) Table 4.12: Indegredient of food of E melanosoma acording to the frequency method No Type of food Number of sample (n=46) Frequency (%) Molluscs 19.57 Crustaceans 8.70 Juveniles 2.20 Other foods 32 69.57 Similar to species of E melanosoma, composition of food consisted of four groups Meanwhile, crustacean appeared as 4.88%, molluscs (12.20%) and juveniles (2.44%), while the other foods (phytoplankton and zooplankton) 16 have very high frequency (100%) (Table 4:13) Table 4.13: Indegredient of food of O urophthalmus acording to the frequency method No Type of food Number of sample (n=46) Frequency (%) Crustaceans 4.88 Molluscs 12.20 Juveniles 2.44 Other foods 41 100 4.3.2.2 Indegredient of food acording to the weigth method Based on the weight of food in the stomach of E melanosoma and numerical analysis for each type of food were defined respectively: molluscs: 70.16; Crustacean: 13.41; fry: 5.63 and others: 0.21 (Table 4:14) Meanwhile, the weigth of each type of food in the stomach of O urophthalmus respectively: molluscs: 13.84; Crustacean: 17.57; fry: fry and 5.21: 0.25 (Table 4:15) Table 4.14: Indegredient of food of E melanosoma acording to the weigth method No Frequency Numerical Type of foods Weigth of food/stomach (g) (%) analysis Molluscs 19.57 3.585 70.16 Crustaceans 8.70 1.541 13.41 Fingerlings 2.20 2.557 5.63 Others 69.57 0.003 0.21 Table 4.15: Indegredient of food of O urophthalmus acording to the weigth method No Weigth of food/stomach Numerical Type of foods Frequency (%) (g) analysis Molluscs 4.88 3.390 13.84 Crustaceans 12.20 1.722 17.57 Fingerlings 2.44 2.553 5.21 Others 100 0.003 0.25 Rate (%) 78.5 15.0 6.3 0.2 Rate (%) 37.5 47.7 14.1 0.7 In nutritional spectrum of E melanosoma molluscs group has the highest percentage (78.5%), crustaceans (15.0%), juveniles (6.3%) and other foods (0.2%); whereas of O urophthalmus was crustaceans group with the highest percentage (47.7%, molluscs (37.5%), juveniles (14.1%) and other foods (0.7%) (Figure 4.12) According to Watts (2004), favorite food was small fish, molluscs and crustaceans, and according to Le Thi Ngoc Thanh (2010), crustaceans and small fish has about 30% of O urophthalmus Crustaceans (15.0%) Fingerlings (6.3%) Fingerlings (14.1%) Others (0.2%) Others (0.7%) Molluscs (37.5%) Molluscs (78.5%) Crustaceans (47.7%) Eleotris melanosoma Oxyeleotris urophthalmus Figure 4.12: Nutritional spectrum of E melanosoma and O urophthalmus 17 4.4 Study on reproductive biology of Eleotris melanosoma and Oxyeleotris urophthalmus 4.4.1 The sexual maturity of E melanosoma and O urophthalmus 4.4.1.1 Stages of the sexual maturity Rate of sexual maturity of E melanosoma was different in months Stage I and II differred from January to March and from July to September, rate of sexual maturity maximum from October to December (68-82%) (Figure 4.13), stage IV appeared throughout the year and the highest since April to June (50%) According to Nguyen Kim (2012), the E melanosoma eggs appeared much from March to June and October to December and female gonads highest stage IV in May and June (50%) The results showed that breeding season of E melanosoma focused in rainy season, starting in May and ending in October, focusing on May to July The stages of sexual maturity of O urophthalmus varied over time In stage I and II appeared from December to Febuary (Figure 4.12), stage IV also appeared throughout the year and the highest from May to June (45%), which showed that breeding season of O urophthalmus was whole year and concentrate from April to June, they usually appear in the flood season (from August to October) and this time is the main crop appearance their (Hajisamae, 2006) Stage III Stage IV Stage I II 100 90 90 80 80 70 70 Percentage ( %) Percentage ( %) Stage IV 100 60 50 40 30 Stage III Stage I II 60 50 40 30 20 20 10 10 0 8/2012 9/2012 10/2012 11/2012 12/2012 1/2013 2/2013 3/2013 4/2013 5/2013 6/2013 7/2013 8/2012 9/2012 10/2012 11/2012 12/2012 1/2013 2/2013 3/2013 4/2013 5/2013 6/2013 7/2013 Month Month Eleotris melanosoma Oxyeleotris urophthalmus Figure 4.13: Percentage (%) stages of sexual maturity of E melanosoma and O urophthalmus 4.4.1.2 Stages of the ovary development of E melanosoma and O urophthalmus Stages of the ovary development were determined up to stage IV (Nikolsky, 1963) Observed with the eyes in stage I and II were difficult to identify, when the matured to stage III and IV easily identifiable and this time the surface of the ovary appear small blood vessels, the color begins moving from bright yellow to pale yellow (Figure 4.14) 18 Stage I of the ovary Stage II of the ovary Stage III of the ovary Stage IV of the ovary Stage I of the ovary Stage III of the ovary Stage II of the ovary Stage IV of the ovary Eleotris melanosoma Oxyeleotris urophthalmus Figure 4.14: Morphology of the ovary development stage of E melanosoma and O urophthalmus The development ovary stages of E melanosoma and O urophthalmus was also determined by histological methods Their gonads stage I easily observed on whole cell slice ovum, the big round, with a larger percentage volume stage II oocytes Size of stage II oocytes increases, and the cell's rate reduction, sharp particles of hematoxylin purple emulsion Stage III switch to oocyte growth nutrients, oocytes begin the accumulation stage, there was many vacuoles appear unstained, the big catch light purple, size increase oocyte, cytoplasmic popularity but weak alkaline, yolk appears more pink eosin Stage IV oocytes size increases, the number of nodes in human urine decreased and disappear into human services, the size maxima oocytes, cell nucleus has no fixed shape (Figure 4.15) Tissue sample at objective lens x10 : Natural ovum cell: ratio of cell nucleus > cells, cytoplasmic staining of Haematoxylin : Oocyte: size increases, the ratio between nuclear and cell reduced, emulsion particles purple color of hematoxylin Tissue sample at objective lens x10 : Natural ovum cell: ratio of cell nucleus > cells, cytoplasmic staining of Haematoxylin : Oocyte: size increases, the ratio between nuclear and cell reduced, emulsion particles purple color of hematoxylin Phase I of the ovary Phase I of the ovary Phase II of the ovary Phase II of the ovary Tissue sample at objective lens x10 Tissue sample at objective lens x10 : Vacuoles are interspersed in the yolk : Cell nucleus : Yolk particles Phase III of the ovary : Vacuoles are interspersed in the yolk : Cell nucleus : Yolk particles Phase III of the ovary Phase IV of the ovary Phase II of the ovary Eleotris melanosoma Oxyeleotris urophthalmus Figure 4.15: Tissue sample stages gonad development of E melanosoma and O urophthalmus 4.4.1.3 Stages of the spermatorrhoea development of E melanosoma and O urophthalmus Morphology of E melanosoma and O urophthalmus based on Nikolsky (1963) include: spermatorrhoea immature stage and mature spermatorrhoea stage: (i) Stage of spermatorrhoea immature: spermatorrhoea shape fiber, stool small lobes, located hugging the fish spine, observed with the naked 19 eyes is difficult to determine the stage of development of spermatorrhoea, and (ii) Stage of mature spermatorrhoea: spermatorrhoea expand and increase size, surface tension spermatorrhoea bulging and rounded, observed with the naked eye can see inside the sperm contains milky Spermatorrhoea stage of immature Spermatorrhoea stage of mature Spermatorrhoea stage of immature Spermatorrhoea stage of mature Eleotris melanosoma Oxyeleotris urophthalmus Figure 4.16: Spermatorrhoea of E melanosoma and O urophthalmus immature and mature stages The development stages of E melanosoma and O urophthalmus was also determined by histological methods In stage spermatorrhoea appear immature reproductive cells early stages of the process of creating crystal, crystal cell level 1, level and sperm Meanwhile, stage of spermatorrhoea mature only mature sperm come out of cysts, large gonialblast and ends the process of creating crystal (Figure 4:17) Tissue sample at objective lens x40 : Gonialblast, cytoplasmic staining of Eosin pinkis : Crystalline cells of primary : Crystalline cells of secondary : Spermatid The sperm cells of primary, secondary and spermatid have purple blue of Heamatoxylin Eleotris melanosoma Oxyeleotris urophthalmus Figure 4.17: Tissue sample stages spermatorrhoea development of E melanosoma and O urophthalmus 4.4.2 Gonadosomatic index and hepatosomatic index Gonadosomatic index (GSI) and hepatosomatic index (HSI) of E melanosoma and O urophthalmus determined from August 2012 to July 2013 Results showed that GSI and HSI of E melanosoma fluctuate more males and females from August to October (Figure 4.18 and Figure 4.19) The highest from May to October and HSI lowest in July, conditional factor (CF) was highest in April and November (Figure 4.18) Meanwhile, GSI of O urophthalmus more than HSI (from June to October), GSI of males from 0.14% to 1.71% and females from 1.59% to 9.70% (Figure 4:18 and Figure 4.19) HSI of O urophthalmus from 0.26% to 2.06% (in male) and from 0.74% to 7.58% (in females) (Figure 4.19) According to Pham Thanh Liem and Tran Dac Dinh (2004), sexual maturity factor and accumulated energy systems of fish were an important factor to predict spawning season and was mainly based on gonad fish to determine 20 14 14 Male Female Male 10 GSI (%) 12 10 GSI (%) 12 Female 6 4 2 0 8/2012 9/2012 10/2012 11/2012 12/2012 1/2013 2/2013 3/2013 4/2013 5/2013 6/2013 7/2013 8/2012 9/2012 10/2012 11/2012 12/2012 1/2013 2/2013 3/2013 4/2013 5/2013 6/2013 7/2013 Month Month Eleotris melanosoma Oxyeleotris urophthalmus Figure 4.18: GSI of E melanosoma and O urophthalmus 14 14 Male Female Male 12 10 10 8 HSI (%) HSI (%) 12 Female 2 8/2012 9/2012 10/2012 11/2012 12/2012 1/2013 2/2013 3/2013 4/2013 5/2013 6/2013 7/2013 8/2012 9/2012 10/2012 11/2012 12/2012 1/2013 2/2013 3/2013 4/2013 5/2013 6/2013 7/2013 Month Month Eleotris melanosoma Oxyeleotris urophthalmus Figure 4.19: HSI of E melanosoma and O urophthalmus 4.4.3 Conditional factor (CF) CF of male E melanosoma was highest in April and November (CF=0.04) and smallest in December (CF=0.01), CF of O urophthalmus was highest CF 0.03 (females) and lowest was 0.01 CF was determined by the coefficient of correlation between the length and weigth of them and assess the level of increase in the weigth of gobies than the length (King, 1995) 0.055 0.055 Female Male Female 0.050 Male 0.050 0.045 0.045 0.040 0.040 0.035 CF (g/cm) CF (g/cm) 0.035 0.030 0.025 0.020 0.030 0.025 0.020 0.015 0.015 0.010 0.010 0.005 0.005 0.000 8/2012 9/2012 10/2012 11/2012 12/2012 1/2013 Month 2/2013 3/2013 4/2013 5/2013 6/2013 7/2013 0.000 8/2012 9/2012 10/2012 11/2012 12/2012 1/2013 2/2013 3/2013 4/2013 5/2013 6/2013 7/2013 Month Eleotris melanosoma Oxyeleotris urophthalmus Figure 4.20: CF of E melanosoma and O urophthalmus 4.4.4 Rate of male and female By analyzing 125 samples of E melanosoma showed that having 45 males, 64 females and 16 samples were not to determine the gender Percentage of male E melanosoma accounted for 41% lower females (59%) Similarly, species of O urophthalmus analyzed 106 samples and 47 samples females (60%), 31 samples males (40%) and 28 samples were not to determine the gender However, by statistical analysis (χ2, 109 samples of E melanosoma and 78 samples of O urophthalmus) showed that the male and female ratio observed in experimental conditions was no difference statistically 21 significant compared to rates expect (1:1) 4.4.5 Fecundity of E melanosoma and O urophthalmus Fecundity of E melanosoma and O urophthalmus were determined based on ovaries developed stage IV Fecundity of E melanosoma was 551±363 eggs/g females in length of 7.2±1.2 cm/ind., weight was 5.26±2.97 g/ind Fecundity of O urophthalmus was 187±134 eggs/g females, lower compare to E melanosoma (44-477 eggs/g females) in body length was 10.1±1.5 cm/ind and 12.31±6.14 g/females Compared with Fouda (1993), fecundity of them similar to red goby (152-782 eggs/g females) and lower compare to some gobies living in the Mediterranean (293-1,300 eggs/g females) with weigth of 603 eggs/g females 4.4.6 Mature length of E melanosoma and O urophthalmus By analyzing 139 samples males and 99 females samples of E melanosoma showed the maturity length (Lm) was 8.62 cm (in males) and 7.79 cm (in females) (Figure 4.21) Meanwhile, Lm of O urophthalmus larger than E melanosome, little difference between males and females in the same populations, Lm of O urophthalmus was Lt=11.36 cm (in male) and Lt=7.97 cm (in female) (Figure 4.22) According to King (1995), father of the length at which gobies populations have 50% of individuals in the colony had grown to maturity stage (stage III) 1.0 1.0 L: Total length (cm) P: Maturation rate reached 50% of goby stocks P: tỉ lệ cá thành thục đạt đến L: chiều dài toàn thân cá (cm) 0.8 P: tỉ lệ cá thành thục đạt đến 50% quần đàn 0.8 50% quần đàn 0.7 trịtrịPP of PGiá ValueGiá 0.7 0.6 -0,532356*(L-8,62496) P=1/{1+e 0.5 } R=0,961 n=139 0.4 P 0.6 P L:L:Total Totallength length(cm) (cm) P:P:Maturation Maturationrate ratereached reached50% 50% ofofgoby gobystocks stocks L: chiều dài toàn thân cá (cm) 0.9 trịtrịPP Giá ofPPGiá Value Valueof 0.9 -0,532356*(L-8,62496) P=1/{1+e 0.5 } R=0,961 n=139 0.4 0.3 0.3 0.2 0.2 0.1 0.1 0.0 0.0 2 10 Giá trị of L L Value 11 12 13 14 15 16 10 Giá trị of L L Value 17 11 12 13 14 15 16 17 Value of L L L Male Female Figure 4.21: Mature length of E melanosoma 1.0 L: Total length (cm) P: Maturation rate reached 50% of goby stocks -0,335283*(L-(11,3551) P=1/{1+e } R=0,953 n=180 P 0.6 0.5 0.4 of P Value trị Giá Giá trị PP 0.7 1.0 1.0 L:L:Total (cm) chiều dàilength toàn dài toàn thân thân cá (cm) cá (cm) 0.9 0.9 L: chiều P: Maturation rate reached 50% 0.8 0.8 P:of tỉP: lệ tỉcálệthành cá thành thụcthục đạt đến đạt đến goby stocks 50%50% trong quầnquần đàn đàn 0.7 0.7 L: chiều dài toàn thân cá (cm) 0.6 0.6 P: tỉ lệ cá thành thục đạt đến 50% quần đàn 0.5 0.5 P 0.8 Giá Giá trị trị PP P of PP Value Giá Giá trị trị P 0.9 0,3865*(L-(7,96827 0,3865*(L-(7,96827 ) ) P= 1/{1+e P= 1/{1+e R=0,955 R=0,955 n=286 n=286 0.4 0.4 0.3 0.3 0.3 } } 0.2 0.2 0.2 0.1 0.1 0.1 0.0 10 11 Male 12 13 Giá trịofL L Value L 14 15 16 17 18 19 20 0.0 0.0 0 2 4 6 Giá 10L 10L Giá trị trị Value of L L 12 12 14 14 16 16 18 18 20 20 L Female Figure 4.22: Mature length of O urophthalmus CHAPTER 5: CONCLUSION AND RECOMMENDATION 5.1 Conclusion In Bassac river, values of pH ranged from 7.0 to 8.5; temperature: 27-33oC; 22 salinity in the downstream appeared in February, June and December, the lowest in rainy season (0-7.6‰) highest dry season (2-10.8‰), the water flow in rainy season higher dry season (0.1-1.3 km/hour), the depth in the middle higher upstream and downstream (4.3-14.4 m) Structure of aquatics in the upstream and middle was higher than that in the downstream The phytoplankton in the upstream has 31 species, middle had 22 species and downstream has 15 species, Bacillariophyta was dominated The zooplankton in the upstream had 33 species, middle had 35 species and downstream had 68 species, in which protozoa was dominated The zoobenthos in the upstream had 17 species, middle had 23 species and downstream had 17 species, gastropoda was dominated There were five species of Eleotridae living in Bassac river including: Eleotris melanosoma, Oxyeleotris urophthalmus, Oxyeleotris marmorata often appear in the upstream, middle and downstream, while species of Butis Butis appeared in the middle and downstream and species of Butis humeralis appeared only in the downstream However, when we catch by trawl species of E melanosoma had in the upstream and downstream, while species of Butis butis appeared only in the downstream and the abundant in rainy sean higher in dry season Species of E melanosoma and O urophthalmus had intestinal length shorter body length, feeding habits of their was animals Their food spectrum relatively, including: crustaceans (78.5%; 37.5%), molluscs (15.0%; 47.7%), juveniles (6.3%; 14.1%) and other foods (0.2%; 0.7%) Gonadosomatic index of E melanosoma and O urophthalmus was high from May to October and hematosomatic index of their was lowest in July, conditional factor was highest in April and November Their breeding was season from May to October, focused from May to July Absolute fecundity of E melanosoma was 2,981-19,520 eggs/female; O urophthalmus ranged 1,290-9,999/female, relative fecundity E melanosoma was 49-930 eggs/g female higher than O urophthalmus (44-477 eggs/g female) Length of mature (Lm) of E melanosoma was 8.62 cm (male) and 7.79 cm (female); while Lm of O urophthalmus was 11.36 cm (male) and 7.96 cm (female) 5.2 Recommendation Study on artificial reproductive of Eleotris melanosoma and Oxyeleotris urophthalmus was able to develop into farmed Study on ability of salt tolerance and some biological characteristics of Butis humeralis was able to develop into the cultured species, contributing to diversification of cultured species in coastal areas and adaptation to climate change 23 PUBLICATIONS Journal 1) Vo Thanh Toan and Ha Phuoc Hung, 2013 Study on species composition and abundance of Eleotridae on Bassac river Journal of Can Tho University Part B: Agriculture, Fisheries and Biotechnology ISSN: 1859-2333, No 28, pages 168-176 2) Vo Thanh Toan and Tran Dac Dinh, 2014 Some biological characteristics of Eleotris melanosoma distributed along Bassac river Scientific Journal of Can Tho University ISSN: 1859-2333, topic on Fisheries (2014) (1), pages 115-122 3) Vo Thanh Toan, Tran Dac Dinh and Nguyen Thi Kim Lien, 2014 Study on nutritional characteristics of Oxyeleotris urophthalmus distributed along Bassac river Scientific Journal of Can Tho University ISSN: 1859-2333, topic on Fisheries (2014) (2), pages 192197 Conferences 1) Vo Thanh Toan, Tran Dac Dinh and Duong Thi Hoang Oanh, 2014 Study on nutritional characteristics of Eleotris melanosoma distributed along Bassac river Proceedings of the science in the national scientific conference on marine biology and sustainable development II ISBN: 978-604-913-259-9 Publisher natural sciences and technology, pages 507-514 2) Vo Thanh Toan, Tran Dac Dinh and Mai Viet Van, 2014 Some biological characteristics of Oxyeleotris urophthalmus distributed along Bassac river Proceedings of the science in the national scientific conference on marine biology and sustainable development II ISBN: 978-604-913-259-9 Publisher natural sciences and technology, pages 515-522 3) Vo Thanh Toan and Tran Dac Dinh, 2015 Some of biology characteristics of the goby Eleotris melanosoma Bleeker, 1853 in bassac river, Vietnam 5th IFS 2015 International Fisheries Symposium Programme and abstract book 1st-4th December 2015 The Gurney Hotel Penang Malaysia Page 358 24 [...]... locations in Bassac river in the upstream, middle and downstream These locations were showned in Table 4.5, Table 4.6 and Table 4.7 Table 4.5: Coordinates of sampling locations in the upstream Location Rivers Location 1 Main river (Long Binh wards , An Phu district) Location 2 Main river (Khanh An wards , An Phu district) Location 3 Main river (Binh Hoa wards, Long Xuyen city) Location 4 Small river (Binh... appear in the upstream, middle and downstream, while species of Butis Butis appeared in the middle and downstream and species of Butis humeralis appeared only in the downstream However, when we catch by trawl species of E melanosoma had in the upstream and downstream, while species of Butis butis appeared only in the downstream and the abundant in rainy sean higher in dry season Species of E melanosoma and. .. butis appeared only in the downstream CPUEn of E melanosoma in dry season ranged 1-173 ind./ha and was lower in rainy season (2-343 ind./ha), CPUEn of the highest and fluctuated more in the upstream and middle (Figure 4.10); CPUEn of B butis appeared only in the downstream very low quantities, CPUEn of B butis in dry season ranges from 1-21 ind./ha and higher than in rainy season (3-6 ind./ha) 400 250... dominated The zooplankton in the upstream had 33 species, middle had 35 species and downstream had 68 species, in which protozoa was dominated The zoobenthos in the upstream had 17 species, middle had 23 species and downstream had 17 species, gastropoda was dominated There were five species of Eleotridae living in Bassac river including: Eleotris melanosoma, Oxyeleotris urophthalmus, Oxyeleotris marmorata often... 0 6±13 4.2 Study on species of Eleotridae and abundance (CPUE) some of gobies in Bassac river 4.2.1 List of species (Eleotridae) There were five species appeared included: Eleotris melanosoma, Oxyeleotris urophthalmus, Oxyeleotris marmorata, Butis humeralis and Butis butis In which, species of B humeralis appeared only in areas downstream and species of B Butis appeared in the upstream and downstream;... g/ha lower than in rainy season (2.3 to 450.5 g/ha) and highest in the upstream (Figure 4.10) Meanwhile, CPUEw of B butis was from 2.6 to 89.7 g/ha and higher than in rainy season (from 8.8 to 13.9 g/ha) (Figure 4.11) The abundant of E melanosoma in rainy season than more in dry season, in the upstream more fluctuation in the middle, while species of B butis appeared in the downstream and it was less... throughout the year and the highest since April to June (50%) According to Nguyen Kim (2012), the E melanosoma eggs appeared much from March to June and October to December and female gonads highest stage IV in May and June (50%) The results showed that breeding season of E melanosoma focused in rainy season, starting in May and ending in October, focusing on May to July The stages of sexual maturity of O... rainy season (0-7.6‰) highest dry season (2-10.8‰), the water flow in rainy season higher dry season (0.1-1.3 km/hour), the depth in the middle higher upstream and downstream (4.3-14.4 m) Structure of aquatics in the upstream and middle was higher than that in the downstream The phytoplankton in the upstream has 31 species, middle had 22 species and downstream has 15 species, Bacillariophyta was dominated... (+): Number of species appear less (