MINISTRY OF EDUCATION AND TRAINING CAN THO UNIVERSITY DOCTORAL DISERTATION SUMMARY Major Aquaculture Major code 62 62 03 01 NGUYEN HOANG THANH IMPROVING QUALITY OF SNAKESKIN GOURAMI FISH Trichogaster[.]
MINISTRY OF EDUCATION AND TRAINING CAN THO UNIVERSITY DOCTORAL DISERTATION SUMMARY Major: Aquaculture Major code: 62 62 03 01 NGUYEN HOANG THANH IMPROVING QUALITY OF SNAKESKIN GOURAMI FISH Trichogaster pectoralis (Regan, 1910) BY SELECTION METHODS Can Tho, 2022 THE RESEARCH WAS PERFORMED AND CAN THO UNIVERSITY Supervisor: Assoc.Prof Duong Nhut Long Co-supervisor: Assoc.Prof Duong Thuy Yen The dissertation will be defended at the Doctoral Dissertation Assessment Committee at the Institute Level At:………………………………………………………… Time & Date:……………………………………………… Reviewer 1: Assoc.Prof Dr Le Van Dan Reviewer 2: Dr Nguyen Van Sang The dissertation can be found at: The learning Resource Center, Can Tho University The national library of Viet Nam THE LIST OF PUBLISHED PAPERS Nguyen Hoang Thanh, Duong Nhut Long and Duong Thuy Yen, 2019 Comparison of growth and survival rates of snakeskin gourami Trichopodus pectoralis (Regan, 1910) at nursery stage from three broodstock sources Science Journal of Can Tho University 55(3B): 96-102 Nguyen Hoang Thanh, Duong Nhut Long and Duong Thuy Yen, 2021 Effect of broodstock on growth and survival rate of snakeskin gourami at grow-out stage Vietnam Science and Technology Magazine Number 01(122): 120-124 Nguyen Hoang Thanh, Duong Nhut Long and Duong Thuy Yen, 2021 Evaluation of effectiveness of selecting snakeskin gourami Trichopodus pectoralis (Regan, 1910) Vietnam Science and Technology Magazine Number 04(125): 150-156 CHAPTER INTRODUCTION 1.1 Background The snakeskin gourami Trichogaster pectoralis (Regan, 1910), also known as the snakeskin gourami fish sặc bổi, lò tho, is distributed in countries in South Asia and Southeast Asia such as India, Indonesia, Malaysia, Thailand, Cambodia and Vietnam (Khoa and Huong, 1993) This is a freshwater fish with economic value and delicious meat quality, so it is favored by many consumers At present, snakeskin gourami fish is becoming an important species of farming, providing raw materials for dry processing in many provinces and cities in the Mekong Delta The source of fingerlings provided to farming models is still limited, the fingerlings are produced from the farmer themselves, the broodstock are used over many times of reproduction, which easily leads to a decrease in the quality of the fingerlings, the fish is easily damaged Infections, low survival rates, productivity and quality of farmed fish are affected (Long et al , 2014) However, in the actual production of snakeskin gourami in the locality, the Mekong Delta as well as in other countries in the region and the world, so far there have not been many studies interested in research and selection of quality snakeskin gourami varieties High quality to provide farmers effectively Therefore, research selection to improve fish growth have great socio-economic significance, contributing to improving productivity and profits for producers Among the breeding methods, the mass selection method has the advantage of being simple, widely applicable and quite convenient in hatcheries, and has a high probability of success in many species fish Although this method has the disadvantage that it is possible that the selected fish are related, leading to inbreeding in the next generation This disadvantage can be mitigated by creating initial populations of fish from different sources and spawning with a large number of broodstock Therefore, the research work with the method of mass selection can be successfully applied to the snakeskin gourami 1.2 Objectives 1.2.1 General Objectives Selected of fish with high quality for growth and spawn from local sources of snakeskin gourami, serving as a scientific basis for forming a process of snakeskin gourami seed production to serve the needs of providing seed for farmers fish in the Mekong Delta 1.2.2 Specific goals - Objective 1: Evaluation of the genetic diversity of snakeskin gourami distributed in different geographical regions in the Mekong Delta (Ca Mau, Kien Giang, Dong Thap) - Objective 2: Select a population of snakeskin gourami with actual heritability (h2) with good growth rate and survival rate as well as productivity in intensive culture model 1.3 Research content a) Evaluation on current situation of snakeskin gourami in 2016 and 2020 in three provinces of Ca Mau, Kien Giang and Dong Thap b) Assessment of genetic diversity of wild snakeskin gourami populations (G) c) Establishing G0 crossbreeds and evaluate the growth of G0 fish from different broodstock sources d) Selection of G0 fish and assessment of quality (genetics, growth) of selected fish 1.4 Scientific significance and applicable ability of the diddertation - Scientific significance: The thesis has assessed the current status of breed production and rearing, the quality of the breeders and the demand for quality fingerling of the producers as a basis for the selection and breeding The thesis has also successfully applied the ISSR molecular marker to evaluate the genetic diversity and differences between starting materials, farmed fish (Dong Thap-DT) and natural sources (Kien Giang-KG) and Ca Mau – CM) The thesis has also assessed the maturation and reproductive criteria of primary materials and populations G0; growth, survival and stocking of fingerlings and commercial fish of combination from primary sources and of selected G0 (CL) flocks compared with control – DC (randomized) as the basis for selectively growing fast G0 and G1 herds - Practical significance: The results of the assessment of the current status of broodstock production and farming of snakeskin gourami, the quality of the fingerlings and the producer's demand for quality fingerlings can be used for management; techniques of applying molecular markers ISSR to evaluate genetic diversity and differences of snakeskin gourami can be applied to research and teaching; G0 and G1 breeding populations can be used for the next selection of varieties, thereby serving production CHAPTER METHODOLOGY 2.1 Content 1: Evaluation on current situation of snakeskin gourami in 2016 and 2020 in three provinces of Ca Mau, Kien Giang and Dong Thap Conduct direct interviews with farmers using the prepared questionnaires in the following table: Table 2.1: Number of questionnaires to interview farmers in Dong Thap, Kien Giang and Ca Mau provinces Orther Year Provinces 2016 50 50 30 Dong Thap Kien Giang Ca Mau 2020 18 12 17 Through survey, direct interview, primary data collection related to technical parameters related to sources of snakeskin gourami in Dong Thap, Kien Giang and Ca Mau From there to serve the process of selective research 2.2 Content 2: Assessment of genetic diversity of wild snakeskin gourami populations (G) The source of snakeskin gourami (G) was obtained from sources (populations): (1) wild fish in Ca Mau; (2) wild fish in Kien Giang; and (3) fish farmed in Dong Thap Each source collects 150-200 pairs, weighing ≥70 g/fish Sample collection period is from January to March 2016 Methods to assess genetic diversity The genetic diversity of three populations of snakeskin gourami was assessed using the ISSR (inter-simpe sequence repeat) marker Based on primers with the most polymorphic results used in the study of some authors (Table 2.2) Table 2.2: Primer sequences were screened to select the best primers Primer Number attachmen Sequenc of Orther t Reference primers e (5'– 3') Nucleotid temperatu es re ( C) Paterson et (CA) al , 2009; 17898B 48 55 Wolfe et al , GT 1998 Fernandes(GGAC) Micro11 48 55 Matioli et al , 2000 (GGAC) ChiuPazza et al , 45 48 A SSR1 2007 (CAC) Sharma et ISSR11 forty six 48 al , 2011 GC (GGAC) ChiuPazza et al , forty six 48 A SSR2 2007 (GTG) Labastida et EL03 forty six 48 al , 2015 GC DNA extraction method Agarose electrophoresis to check the quality of extracted DNA DNA amplification (PCR) ISSR molecular genetic data processing method ISSR data were processed using GenAlEx 6.5 software (Peakall and Smouse, 2012) and Popgene 1.3 (Yeh et al , 1999) 2.3 Content 3: Establishing G0 crossbreeds and evaluate the growth of G0 fish from different broodstock sources 2.3.1 Stimulation of artificial spawning and pairing of snakeskin gourami with combinations from sources fish Broodstock fish from three sources Ca Mau (CM), Kien Giang (KG) and Dong Thap (DT) for diallel cross Table 2.3: Combinations of snakeskin gourami Combination CM (♂) KG (♂) ĐT (♂) CM (♀) ♀CMx♂CM ♀CMx♂KG ♀CMx♂ĐT KG (♀) ♀KGx♂CM ♀KGx♂KG ♀KGx♂ĐT ĐT (♀) ♀ĐTx♂CM ♀ĐTx♂KG ♀ĐTx♂ĐT 2.3.2 Effect of fish source and mating method on growth and survival rate of snakeskin gourami at the nursery stage - Experimental survey time, especially in Ca Mau and Dong Thap provinces 3.2 Genetic diversity of native fish resources Analysis of three populations of snakeskin gourami fish in Ca Mau, Kien Giang and Dong Thap based on six inter-simple sequence repeats (ISSR) markers (bait) showed 56 bars, the population of snakeskin gourami distributed in Ca Mau area had the highest genetic diversity, expressed through the parameters of polymorphic gene ratio (78.21%), mean number of alleles (1.74±0.059), heterozygosity rate ( 0.238±0.021) and Shannon index (0.389±0.021) Farmed fish in Dong Thap and wild fish in Kien Giang have similar polymorphic genes ( 66.67%, 66.67%) and average number of alleles (1.615±0.066, 1.615±0.066) effective allele (1.332±0.040; 1.394±0.044), heterozygosity (0.203±0.022; 0.232±0.023) and Shannon index (0.306±0.031; 0.341±0.032) were lower than those of Ca Mau fish stocks However, the level of difference in genetic diversity between these three populations of snakeskin gourami is not large The genetic differences of the three sources of snakeskin gourami were reflected in the genetic distance or level of similarity between the fish sources The three sources of snakeskin gourami had a high level of similarity (from 0.964 to 0.993) or low 14 genetic distance (0.007–0.036) The genetic distance of fish sources in Dong Thap is higher than between those two sources (Ca Mau–Kien Giang) This relationship is shown through the genetic tree, the two sources Ca Mau and Kien Giang have near the genetic distance, located in the same branch, while the Dong Thap fish source is in a separate branch This may be due to the domestication of snakeskin gourami (the result of an investigation into the source of Dong Thap snakeskin gourami domesticated over generations) that has resulted in genetic changes compared with the wild fish population (fish in Ca Mau and Kien Giang province) Cà CaMau Mau Kiên KienGiang Giang Ðong Tháp Dong Thap 0.5 Figure 3.1: Genetic tree by UPGMA (Unweighted Pair Group Method with Arithmetic Mean) of three populations of snakeskin gourami From the results of analysis of the genetic diversity of the populations of snakeskin gourami distributed in Ca Mau, Kien Giang and Dong Thap provinces, there are differences in diversity genetics 15 among the populations of snakeskin gourami distributed in different ecological regions in the Mekong Delta, in which the highest genetic diversity is found in the highest genetic diversity was found in Ca Mau's snakeskin gourami, followed by Dong Thap's snakeskin gourami and finally, in Kien Giang's snakeskin gourami group Evaluation of the genetic diversity among populations of snakeskin gourami showed that all three sources of cholera had moderate and similar genetic diversity Therefore, they are likely to contribute the same genetic material when conducting selection to create brood stock populations from the three sources mentioned above 3.3 Results of creating G0 and assessing the growth ability of G0 from different broodstock sources Table 3.1: The results spawn of snakeskin gourami in the mating combinations Reproduction parameters Combin ation KGxKG KGxDT KGxC M Tim e spa wn (hou rs) 21:4 7' 21:1 5' 21:5 4' Fis h spa wn rate (%) 100 100 100 Fertiliz ation rate (%) Hatch ing rate (%) 90.8±1 ab 89.0±4 1a 93.8±4 bc 86.9± 2.8 b 88.6± 3.9 bc 93.9± 3.1 d 16 RF (eggs/kg) 348,539± 68,420 c 271.558± 84,829 a 307,613± 45,138 abc Dimor phic ratio (%) 1.3±0 6a 1.2±0 4a 1.5±0 6a DTxDT DTxKG DTxCM CMxC M CMxK G CMxDT 21:5 5' 22:0 6' 22h 16' 21:3 8' 22:0 5' 21:3 5' 100 100 100 100 100 100 94.2±2 2c 93.6±3 bc 92.8±3 bc 89.0±1 5a 90.8±6 ab 90.7±7 ab 91.5± 2.2 cd 93.1± 3.4 d 93.5± 2.6 d 83.7± 2.3 a 91.4± 4.8 cd 91.1± 7.9 cd 254.636± 70,434 a 241.923± 94,271 a 258,371± 97,718 a 345,088± 90,637 bc 304,958± 80,884 abc 283.304± 77,713 ab 1.3±0 4a 1.4±0 4a 1.4±0 4a 1.5±0 5a 1.5±0 5a 1.5±0 6a The research results show that the fertilization rate, hatching rate and relative fecundity of fish not depend on the male source but mainly on the female source, although in the same source Dong Thap female fish has fertilization rate, hatching rate were higher but the relative fecundity of fish was lower than that of female fish sources in Ca Mau and Kien Giang 3.3.2 The nursery stage results of mating combinations The results after 2.5 months of the nursery stage showed that, in the DTxDT combination of nursery fish, the largest weight (9.26±1.18 g/fish), followed by the KGxKG combination (6.43±1.07 g/fish), the lowest was in the CMxCM combination (4.13±1.20 g/fish) In general, for the nursery stage, the DTxDT combination had a higher daily weight gain and specific growth rate (P