effects of natural foods on food selection and growth rates of cobia (rachycentron canadum) larvae

CAN THO UNIVERSITY COLLEGE OF AQUACULTURE AND FISHERIES EFFECTS OF NATURAL FOODS ON FOOD SELECTION AND GROWTH RATES OF COBIA (Rachycentron canadum) LARVAE By NGUYEN CHI A thesis submitted in partial fulfillment of the requirements for the degree of Bachelor of Aquaculture Can Tho, December 2013 CAN THO UNIVERSITY COLLEGE OF AQUACULTURE AND FISHERIES EFFECTS OF NATURAL FOODS ON FOOD SELECTION AND GROWTH RATES OF COBIA (Rachycentron canadum) LARVAE By NGUYEN CHI A thesis submitted in partial fulfillment of the requirements for the degree of Bachelor of Aquaculture Supervisor Assoc. Prof. Dr. TRAN NGOC HAI Dr. LY VAN KHANH Can Tho, December 2013 APPROVEMENT The thesis “Effects of natural foods on food selection and growth rates of cobia (Rachycentron canadum) larvae” defended by Nguyen Chi, which was edited and passed by the committee on 12-27-2013. Sign of Supervisor Assoc. Prof. Dr. TRAN NGOC HAI Sign of Supervisor Dr. Ly Van Khanh Sign of Student NGUYEN CHI Acknowledgements First of all, I would like to express my honest thanks to the Rectorate of Cantho University and the lecturers of College of Aquaculture and Fisheries for supporting me to study after 4.5 years. I would like to thank Assoc. Prof. Dr. Tran Ngoc Hai, Dr. Ly Van Khanh and Dr. Le Quoc Viet who have instructed me enthusiastically to finish this graduating thesis. For other valuable help and guide, thanks are extended to all my friends, Mr. Pho Van Nghi, Mr. Nguyen Van Thang, Ms. Nguyen Thi Diem Chi, Mr. Nguyen Tuan Cuong and students in AAP course 35. I also send my gratefulness to my advisor Dr. Duong Thuy Yen for her constant support and my beloved classmates in Advanced Aquaculture Program for great encouragement during 4.5 years in CAF. Finally, I thank my family and all my friends who have supported and encouraged me to study and finish my course. I honestly thank all of you! NGUYEN CHI i Abstract The aim of study was to investigate the pattern of food selection and growth rates of cobia (Rachycentron canadum) larvae reared in pond water. The study was based on the stomach analysis of cobia larvae during the larval stage from hatching to 10 days old. Stomach contents were compared to environment composition and electivity indices were calculated. Natural pond water that contained various live organisms such as taxons of rotatoria, copepoda and nauplius were released to the cultured tanks. Four days after hatching, the larvae commenced feeding and showed little selectivity on zooplankton for 10 days. Brachionus plicatilis, Brachionus pala and Nauplius, the main prey organisms were found to be preferred by larvae during from day to day 7, and subsequently replaced by bigger size prey such as Schmakeria clubia and Microsetella norvegica during from day to day 10. After 10 days of rearing, the fries reached the size of about 5.10 – 5.50mm. Daily length gain (DLG) of larvae fluctuated from 0.09 to 0.16mm/day and specific growth rate (SGR) ranged from 2.13 to 3.58%/day. Electivity indices on Nauplius and Schmakeria clubia range from 0.27 to 0.40 and from 0.42 to 0.47, respectively, indicating that Nauplius and Schmakeria clubia were found to be most preffered food for the cobia larvae during for 10 days old. The change on prey selectivity might be due to the mouth size, sluggish movement of this fish at their initial stages. ii TABLE OF CONTENT Acknowledgements . i Abstract . ii TABLE OF CONTENT . iii List of Tables .v List of Figures vi List of abbreviations . vii CHAPTER I .1 1.1 Introduction 1.2 Objectives of the study .2 1.3 Contents of research CHAPTER II .3 2.1 Biological features of Cobia (rachycentrum canadum) 2.1.1 Classification and taxonomy 2.1.2 Habitat and distribution .4 2.1.3 Food and Nutrition .4 2.2 Overview about the status of hatchery and farming production of cobia 2.2.1 Overview about the status of hatchery and farming production of Cobia in the world .6 2.2.2 Overview about the status of hatchery and farming production of Cobia in Vietnam .8 2.3 Food selection of fish 2.4 Types of natural food used for larval nusery 11 2.4.1 Rotifers .12 2.4.2 Copepods .13 CHAPTER III 15 3.1 Time and location 15 3.2 Materials 15 3.2.1 Equipment 15 iii 3.2.2 Water source 15 3.2.3 Feed 15 3.3 Research methodology 15 3.3.1 Experimental design 15 3.3.2 Sampling and data collection .16 3.4 Statistical analysis .19 Data will be analyzed for mean value, standard deviation by using Excel software. 19 CHAPTER IV 20 4.1 Water quality parameters .20 4.2 Growth rates .23 4.3 Food selection of cobia larvae 25 4.3.1 Planktons in rearing tank .25 4.3.1.1 Species composition of planktons in rearing tank 25 4.3.1.3 Percentage composition of zooplankton in rearing water 26 4.3.2 Planktons in stomach of cobia larvae 27 4.3.2.1 Species composition of planktons in stomach of cobia larvae .27 4.3.2.2 Density and amount of zooplankton in stomach of cobia larvae 28 4.3.2.3 Percentage composition of zooplankton in stomach of cobia larvae .30 4.3.3 Electivity index of cobia larvae .31 CHAPTER V .35 5.1 Conlusions 35 5.2 Recommendations 35 Appendix .46 iv List of Tables Table 3.1 Physical and chemical parameter collection…………………………… 18 Table 4.1 Water quality parameters during culture period………………………… 20 Table 4.2 Growth rate of cobia larvae during 10 days……………………………….23 Table 4.3 Composition of zooplankton in rearing tank…………………………… 25 Table 4.4 Density of zooplankton in rearing tank………………………………… 26 Table 4.5 Composition of planktons in stomach of cobia larvae……………………28 Table 4.6 Density of zooplankton in stomach of cobia larvae………………………29 Table 4.7 Amount of zooplankton in stomach of cobia larvae………………………29 Table 4.8 Electivity index of cobia larvae……………………………………………32 v List of Figures Figure 2.1 15 – 20 kg broodstock cobia……………………………………………….4 Figure 2.2 Global aquaculture production of Rachycentron canadum……………… Figure 2.3 Euryhaline Brachionus species used in aquaculture as live food……… .13 Figure 4.1 Variation of temperature during the culture period…………………… 21 Figure 4.2 Variation of pH during the culture period……………………………… 22 Figure 4.3 Variation of water clarity during the culture period……………… .22 Figure 4.4 Variation of TAN during the culture period…………………………… .22 Figure 4.5 Variation of nitrite during the culture period…………………………….23 Figure 4.6 Illustration of cobia larvae growth in 10 days……………………………25 Figure 4.7 Density of zooplankton in rearing tank………………………………… .26 Figure 4.8 Percentage of zooplankton in rearing tank……………………………… 28 Figure 4.9 Density of zooplankton in stomach of cobia larvae………………………30 Figure 4.10 Amount of zooplankton in stomach of cobia larvae…………………….30 Figure 4.11 Percentage of zooplankton in stomach of cobia larvae………………….31 vi List of abbreviations CMFRI………………… Central Marine Fisheries Research Institute HUFA………………………Highly unsaturated fatty acid PUFA……………………….Polyunsaturated Fatty Acid ARA……………………… Arachidonic acid EPA……………………… .Eicosapentaenoic acid DHA……………………… Docosahexaenoic acid PRC………………… .Peoples Republic of China HCG……………………… Human chorionic gonadotropin DLG……………………… Daily length gain SGR……………………… .Specific growth rate TAN……………………… Total ammonia – nitrogen FAO……………………… Food and Agriculture Organization of the United Nations dph…………………… Day post hatch ppt…………………………Part Per Thousand CFU/g…………………… .Colony Former Unit BLi…………………………Initial Body Length BLf…………………………Final Body Length vii CHAPTER V CONCLUSIONS AND RECOMMENDATIONS 5.1 Conlusions - Temperature, pH, transparency, nitrite, TAN in the experiment were in the suitable ranges for the cobia fry. - After 10 days of rearing, the fries reached the size of about 5.10 – 5.50mm. Daily length gain (DLG) of larvae fluctuated from 0.09 to 0.16mm/day and specific growth rate (SGR) ranged from 2.13 to 3.58%/day. - Brachionus plicatilis, Brachionus pala and Nauplius, the main prey organisms were found to be preferred by larvae during from day to day 7, and subsequently replaced by bigger size prey such as Schmakeria clubia and Microsetella norvegica during from day to day 10. Electivity indices on Nauplius and Schmakeria clubia range from 0.27 to 0.40 and from 0.42 to 0.47, respectively, indicating that Nauplius and Schmakeria clubia were found to be most preffered food for the cobia larvae during for 10 days old. 5.2 Recommendations - Need to fertilizer to color in pond water. In order to promote the diversity of natural food sources. Then, natural foods will be filtered through plankton nets to choose prey depending on the mouth size of fish. From the age of to the age 7, the cobia fish need to eat small prey such as rotifers, nauplius. 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Number 10 11 12 13 14 15 16 17 18 19 20 Length of larvae Day Day Day 4.1 4.6 5.5 4.1 4.5 5.3 4.0 4.5 5.0 3.9 4.5 5.1 3.9 4.6 5.0 4.0 4.3 5.1 4.0 4.2 5.0 4.0 4.5 5.2 4.0 4.5 5.2 4.0 4.3 5.2 4.0 4.5 5.2 4.0 4.3 5.2 3.9 4.5 5.2 4.1 4.5 5.2 4.0 4.5 5.2 4.0 4.5 5.1 4.0 4.3 5.0 4.0 4.5 5.1 4.0 4.3 5.0 3.9 4.5 5.0 Day 10 5.2 5.2 5.2 5.2 5.4 5.4 5.4 5.4 5.4 5.4 5.1 5.5 5.5 5.5 5.5 5.1 5.1 5.0 5.1 5.1 Appendix Species density of zooplankton in rearing tank Taxon (inds/L) Rotatoria Brachionus plicatilis Brachionus pala Copepod Laophonte brevirostris Schmakeria clubia Acartia discaudata Microsetella norvegica Nauplius Mean 10 440,000 220,000 513,333 293,333 660,000 366,667 366,667 586,667 440,000 733,333 366,667 953,333 366,667 1,100,000 73,333 73,333 73,333 0 0 73,333 73,333 146,667 73,333 220,000 146,667 220,000 73,333 73,333 146,667 146,667 220,000 146,667 880,000 146,667 1,026,667 293,333 1,466,667 220,000 1,320,000 293,333 1,833,333 366,667 2,200,000 293,333 2,273,333 48 Appendix Species amount of zooplankton in rearing tank Taxon (points/L) 10 Rotatoria Brachionus plicatilis Brachionus pala 440,000 220,000 513,333 293,333 660,000 366,667 366,667 586,667 440,000 733,333 366,667 953,333 366,667 1,100,000 Copepoda Laophonte brevirostris Schmakeria clubia Acartia discaudata Microsetella norvegica 146,667 0 146,667 0 146,667 293,333 0 0 293,333 220,000 586,667 293,333 440,000 880,000 586,667 440,000 880,000 293,333 660,000 Nauplius 146,667 146,667 293,333 220,000 293,333 366,667 293,333 Mean 953,333 1,100,000 1,760,000 1,686,667 2,786,667 3,593,333 3,593,333 Appendix Percentage composition of zooplankton in rearing tank Taxon 10 Brachionus plicatilis 46.15 46.67 37.50 21.74 15.79 10.20 10.20 Brachionus pala 23.08 26.67 20.83 34.78 26.32 26.53 30.61 Laophonte brevirostris 15.38 13.33 8.33 0.00 0.00 0.00 0.00 Schmakeria clubia 0.00 0.00 16.67 0.00 21.05 24.49 24.49 Acartia discaudata 0.00 0.00 0.00 17.39 10.53 16.33 8.16 Rotatoria Copepoda 0.00 0.00 0.00 13.04 15.79 12.24 18.37 Nauplius 15.38 13.33 16.67 13.04 10.53 10.20 8.16 Mean 100.00 100.00 100.00 100.00 100.00 100.00 100.00 Microsetella norvegica Appendix Percentage composition of zooplankton in stomach of cobia larvae Tanxon 10 Brachionus plicatilis 40.00 42.11 30.30 25.64 7.21 4.48 2.86 Brachionus pala 33.33 31.58 39.39 43.59 13.51 11.94 9.71 Laophonte brevirostris 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Schmakeria clubia 0.00 0.00 0.00 0.00 57.66 59.70 64.00 Acartia discaudata 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Microsetella norvegica 0.00 0.00 0.00 0.00 16.22 20.15 20.57 Nauplius 26.67 26.32 30.30 30.77 5.41 3.73 2.86 Mean 100.00 100.00 100.00 100.00 100.00 100.00 100.00 Rotatoria Copepoda 49 50 [...]... production in general and the cobia seed production in particular is very necessary and urgent Based on research and practical demands, this study on Effects of natural foods on food selection and growth rates of cobia (Rachycentron canadum) larvae was carried out to apply in practice 1.2 Objectives of the study To evaluate the effects of natural foods on food selection and growth of cobia larvae at early... to contribute to seed production of cobia fish 1.3 Contents of research - To evaluate water quality and natural food in tanks - To evaluate the growth rates of larvae - To evaluate food selection through food composition in stomach contents at different stages of larvae 2 CHAPTER II LITERATURE REVIEW 2.1 Biological features of Cobia (rachycentrum canadum) 2.1.1 Classification and taxonomy Cobia (Rachycentron. .. selection of cobia larvae 4.3.1 Planktons in rearing tank 4.3.1.1 Species composition of planktons in rearing tank In this study, phytoplankton net was torn So, we were not able to conduct sampling phytoplankton in rearing tank The results of quality analysis of zooplanktons are given in the Table 4.3 Table 4.3 Composition of zooplankton in rearing tank Taxon Rotatoria Brachionus plicatilis Brachionus... survival and growth because the energetic requirements of the larvae are not satisfied (Dowd and Houde, 1980; Tandler and Sherman, 1981) An excessive rotifer density can also decrease larval survival and growth by promoting excessive ingestion of rotifers, hence decreased gut retention time and a subsequent reduction in assimilation efficiency (Boehlert and Yoklavich, 1984; Tandler and Mason, 1984)... life, rapid decline of nutritional quality if stored for too long, unstable supply (depending on the season), relatively low growth rates (compared with pelleted diets (although data is still scare)), localised pollution and water quality degradation, and transmission of parasites and diseases The relative benefits of pelleted diets include faster growth rates (feed to biomass conversion ratios are generally... information is available regarding the nutritional requirements of cobia larvae in recirculating aquaculture systems, 1 and such information is essential to maximize larval growth and survival and further the successful commercial production of this species (Faulk and Holt, 2005) In Vietnam, Cobia is considered the most popular species for culture in offshore cages This is because of its fast growth, ... production of larvae, the current innovation in intensive and super intensive nursery rearing in ponds, and improved formulated feeds However, there are still many difficulties remained, such as environmental and diseases problems as well as limitations when relying on natural seed sources, natural food sources, quantity and quality of the seed Therefore, the study of marine fish seed production in general... accumulation of nutritionally inadequate rotifers, and can cause decreased survival and growth of fish larvae (Lubzens et al., 1989) 2.4 Types of natural food used for larval nusery Nutritional requirements centre the research and hatchery management of larval fish rearing and production (Cahu et al., 2003; Lee, 2003) Currently, the seed supply of fish juveniles in commercial hatcheries relies on the... 2006b) The live food organisms consumed by the larvae assist the digestion process by donating their digestive enzymes to the gut of fish larvae (Dabrowski and Glogowski, 1977; Kolkovski et al., 1993) The nutritional requirements of fish larvae change during the course of ontogenetic development during early life history (Oozeki and Bailey, 1995) The variations of nutritional need depend on the morphology,... the points for each food item are reduced to percentages to show the percentage composition of the diet This method is essentially a numerical one; the volume being only a secondary consideration and it is only in the counts that a certain amount of accuracy can be claimed (P.U Zacharia et al., 2011) Point number of each type of foods depends on: 17 Frequency of occurrence: the food, mostly appeared, . CHAPTER III 15 3.1 Time and location 15 3.2 Materials 15 3.2.1 Equipment 15 iv 3.2.2 Water source 15 3.2.3 Feed 15 3.3 Research methodology 15 3.3.1 Experimental design 15 3.3.2 Sampling. proper development and functioning of neural and visual systems (Kanazawa, 19 97; Rainuzzo et al., 19 97; Sargent et al., 19 97) . Several studies have shown that marine fishes are unable to convert. rearing water 26 4.3.2 Planktons in stomach of cobia larvae 27 4.3.2.1 Species composition of planktons in stomach of cobia larvae 27 4.3.2.2 Density and amount of zooplankton in stomach of cobia