MINISTRY OF EDUCATION AND TRAINING CAN THO UNIVERSITY ♣♣♣ NGUYEN VAN TRIEU THE SCIENTIFIC BASIS OF MATURATION CULTURE AND TECHNOLOGY OF WHISKER CATFISH REPRODUCTION (Micronema bleekeri) Specialization: Freshwater Aquaculture Field of Study Code: 62 62 60 01 Dissertation of Doctor Degree in Aquaculture Cantho, 2014 The study was carried-out at: College of Aquaculture and Fisheries, Can Tho University. Supervisors: Ass/Prof. Dr. Nguyen Anh Tuan Ass/Prof. Dr. Duong Nhut Long Examiner 1: Examiner 2: The dissertation will be defended at the university committee in … at: ….… hr ….… date ……. month ……. year 2014 The disseratation is available in Libraries: Learning Resource Center of Can Tho University. College of Aquaculture, Can Tho University 1 AN OVERVIEW OF THE THESIS 1. Imperative thesis Fresh water aquaculture which is a position of strength in the Mekong Delta includes mainly objects such as tra catfish, climbing perch, snakehead,… However, in recent years, aquaculture has had difficulties because prices which are not usually stable. Therefore, farmers have found some new culture species. As assessment of several farmers both An Giang and Dong Thap provinces that whisker catfish is a species which has had high economic values and prospects for developmental aquaculture, especially in cages culture. Fingerlings which have been depending on nature do not guarantee quality and quantity. These study results about whisker catfish have provided basic data about biological characteristics and technology of artificial reproduction. The contribution of building the process of whishker catfish reproduction which is: “The scientific basis of maturation culture and technology of whisker catfish reproduction (Micronema bleekeri Gunther, 1864)” was carried out. 2. General objectives of thesis To provide scientific data about the technology of gonadosomatic conditioning and whisker catfish reproduction, contributing to production of fingerlings initiatively both quality and quantity for farmers, and objecting diversification and sustainable development of aquaculture in the Mekong Delta. 3. Significance of scientific and reality In the scientific aspect, these studies have provided scientific information about the effective feed to martunity of whiker catfish. Besides, thesis has also studied the capacity of M. bleekeri spawning by different hormones and technology of whisker catfish rearing from fry to fingerling stages. 4. New results of thesis: The first in identifing: Whisker catfish which was conditioned in ponds by trash tiny shrimp will have been maturity in May and June with gonadosomatic index 2 (about 3.8 ± 0.08%) in females and relative fecundity (about 110 ± 9.1 eggs/g female). Through conditioning process that Vitellogenin (Vg) in plasma of female will change proportional with the development stages of gonad. Vg content increased the highest when gonad has changed from III to IV stage and had closely correlation between Vg content and the development of egg diameter in times. Spawning stimulation of M. bleekeri by pituitary with 3.5 mg/kg female; LRHa + Dom (70 µg) + 3.5 mg/kg female; and Ovaprim which was used with 0.3 mL/kg so that fish has had spawning, besides the rates of fecundity, fertilization and hatching was relatively high. Whereas, spawning stimulation by HCG (4,000 – 6,000 UI/kg female) so that 100 % of fish did not ovulate. M. bleekeri started first feeding after two days. From 2 to 5 days, fish was fed by rotifera and copepoda larvae, through 6 – 30 days fish was fed by Cladocera and Copepoda. The rearing of M. bleekeri by tubifex with 3.5 individuals/L so that daily weight gain (20.2 ± 0.25 mg/day) and survival rate (88.9 ± 3.2 %) were relatively high. Whisker catfish was also used well home-made feed at 7 th day. Protein requirement of M. bleekeri fingerlings (sizes of fish about 269 mg) was 43.2 %. The rearing of whisker catfish by pellet (36 % crude protein) with density of 3.5 fingerlings/L at 60 days; which has achieved survival rate and daily weight gain were 81.2 ± 3.5 % and 25.9 ± 0.25 mg/day, respectively. THE STUDY METHODS 3.1. The times and location of study The study was carried out from 2007 to 2011 at the College of Aquaculture and Fisheries, Can Tho University. 3.2. Study object was whishker catfish Micronema bleekeri 3.3. Study methods 3.3.1. Effective feed to maturity of whisker catfish 3.3.1.1. Experiment systems 3 An experiment was carried out in hapas (1 x 1x 1.5 m), sizes of mesh was 0.5 cm; which was put in a pond (500 m 2 ), the depth of water was 1.2 – 1.5 m. 3.3.1.2. Fish of experiment: Whisker catfish was equal sizes and healthy, and the initial weight of fish was 80 – 90 g/fish. 3.3.1.3. Feed of experiment: Trash tiny shrimp and fish, which were crushed and mixed with 1 % of powder of cotton leaves to increase adhisively and pelllets were also wetted by water. Feed was put in ”feeding floors” at the bottom of hapas. 3.3.1.4. Experimental design The experiment including three treatments (T) was completely randomized designed with three replicates. Every hapa was stocked with 20 whisker catfish (the rate of male and female was 1 : 1). The time of experiment was five months. Table 3.1. Component of home-made feed Treatment (T) Component of home-made feed T 1 99% trash tiny shrimp + 1% kapok powder T 2 49.5% trash tiny shrimp+49.5% trash fish+1% kapok powder T 3 100% pellet (29.5 % crude protein) 3.3.1.5. Feeding and taking care of: Whishker catfish was fed demandably, including two times per day at 8 am and 5 pm. 2.3.1.6. Result records Before conducting experimental arrangement, three males and females were chosen contingently to collect the first data. Through experimental process, recurrently every treatment will have sampled contingently, including three males and females to check the maturity of fish through index about the size rates of eggs diameter, the erythrocyte numbers, hemoglobin and vitellogenin contents. These indexes were checked at 30; 60; 90; 105; 120 and 150 days after experimental arrangement. Gonadosomatic index and fecundity of whishker catfish were checked at the times that gonad of fish was 4 th stage. 3.3.2. The technological study of artificial spawning of whishker catfish 4 3.3.2.1. Experimental fish: Healthy whishker catfish with the initial weight of 50 – 100 g/fish. Female: big belly, concave papilla. Whishker catfish has had eggs diameter which was ≥ 0.8 mm was more than 80%. Male: choosing fish which has had slim body, samll belly and pointed papilla. 3.3.2.2. Experimental design Table 3.2: Content of hormone in experimental arrangement Four experiments were completely randomized designed, with four different hormones, every type of hormone has had three content (9 females/repeatedly) (Table 3.2). Male fish was injected by hormone correlatively with each experiment, by 1/3 the content of female. 3.3.2.5. Recording of results: The results of artificial breeding of whishker catfish were evaluated through some indexes: the rate of spawning, the times of effective drugs, fecundity, fertilization rates, and the rates of hatching; which was recorded. 3.3.3. The technological study of whisker catfish rearing from fry to fingerling stages 3.3.3.1. The study of nutritional characteristics of whisker catfish from fry to juvenile a. Experimental pond: The study was carried out in a pond which has had about 12 m 2 (3 x 4 m) in areas, and was coated canvas and muds at bottom about 25 cm, the depth of water was 0.5 m. b. Feed: Before stocking, natural food was cultured by haversacks which have had about 25 µm in mesh and have contained fish meal in some corners of ponds throughout experiment, avoiding fish was eating directly fish meal. Experiment Hormone Content of hormone I II III 1 2 3 4 Hypophysis (mg/kg female) HCG (UI/kg female) LRHa (µg) + Dom (mg)/kg female Ovaprim (ml/kg female) 1.5 4,000 40 + 3.5 0.3 2.5 5,000 70 + 3.5 0.4 3.5 6,000 100 + 3.5 0.5 5 c. Experimental design: Whisker catfish (1 day) which has had average weight and length were 1.73 mg and 5.02 mm, respectively; were stocked in the pond about 600 fish/m 2 in density and the experimental time was 30 days. d. Sampling and analysis Sampling: The samplings of zooplankton and phytoplankton and fish on the day: 1; 2; 3; 4; 5; 6; 8; 10; 15; 20; 25 and 30 after stocking. Fish was sampled contingently about 30 individuals and preserved in formol solution 10%. The analysis of zooplankton and phytoplankton: qualitative analysis based on classification documents of Dang Ngoc Thanh (1980), Han Maosen Shu Yunfang (1995); quantify based on the documents of Duong Tri Dung (1996); Boyd and Tucker (1992). Identified the nutritional characteristics of whishker catfish (1) The rate between intestine and standard length L i /L 0 (2) Identified the sizes of fish mouth (3) Stomach analysis Frequency method: Frequency of food is the rate between stomach which holds this food and the total of stomachs are observed (Hynes, 1950). (4) The food choices of fish Cofficients of food choices are counted by Ivlve’s Electivity index: E = (r i -p i )/(r i +p i ) In there, r i which is the percentage of food type i has found in intestine of fish and p i which is the percentage of food type correlatively has found in environment on the total food which has had in environment. 3.3.3.2. The study of whisker catfish rearing from fry to fingerling Experiment 1: The study of whisker catfish rearing to 30 th day using live food 6 a. Experimental design: Experiment was arranged in the system of plastic bucket about 35 L (held 30 L water). The experiment was completely randomized designed, including four treatments (T) with three replicates: (T1) whisker catfish was fed by tubifex, (T2) whisker catfish was fed by zooplankton, (T3) fish was fed by artemia and (T4) fish was fed the combination between tubifex and zooplankton in the same rate. Fish of experiment was whisker catfish which was two days; healthy, not deformities and mean weight of fish was 1.8 mg. The density of rearing was 2.5 fingerlings/L in 30 days. b. Experimental food: Tubifex is bought by households in Can Tho province. Zooplankton was cultured (was the same with the culture method of live food at the study 3.3.3.1. of section b). After that racket was used to let through for fish which ate gradually through out the experiment. Larvae of newly-hatched artemia were collected through the incubation process of cyst artemia about 15 ‰ in salinity for 24 hours. e. Feeding and taking care of: Fish was fed by demand, including two times per day at 8 am and 5 pm. f. Result records Environmental factors such as temperature, oxy, pH; which were identified by 556 YSI – USA, two times per day. Before arranging experiment, 30 of fry whishker catfish were scaled to indentify the first weigh. When the experiment has finished, most of fish will have scaled by electronic weight to identify: daily weigh gain (DWG, g/ngày), specific growth rate (SGR, %/ngày) and survival rate. Experiment 2: The study of whisker catfish rearing by Tubifex at different densities. a. Experimental arrangment: Experiment fish (2 days) was arranged contingently in plastic bucket about 35 L (held 30 L water), including four treatments that densities were 1.5; 3.5; 5.5 and 7.5 individuals/L, respectively, repeated three times. The time of experiment was 30 days. 7 b. Food of experiment: Food for fish in this experiment was tubifex which was cut smoothly (the best result in experiment of 1). Experiment 3: The study of times that whisker catfish has used effectively home-made feed a. Experimental design: Experiment was carried out in plastic bucket about 35 L (held 30 L water). Whisker catfish (2 days) was arranged in bucket with 2.5 individual/L in density. Experiment was carried out about 30 days, including six treatments which were arranged contingently with repeating three times. All treatments differed by the first day of feeding home-made, including the day 1; 3; 5; 7; 9 and 11 after arranging experiment. Table 3.5: Nutritional component of home-made feed Component % of dry matter Protein Lipid Moisture Ash 36.1 31.7 10.6 6.89 b. Food of experiment: Components of home-made feed included: trash fish (100 g), unfatty milk (100g), egg yolk (10 eggs), squid oil (3%). Most materials were husked, steamed, pressed fiber, dried up and kept in cold store. Fish was fed three hours per once based on their demands. Experiment 4: The study of whisker catfish rearing by pellets at different densities a. Experiment systems: Experiment was arranged in cement tanks with 1 m 3 (held about 600 L water). b. Fish of experiment: Fish in the experiment was whishker catfish of 7 days and mean weight was 13.1 mg, weaned by pellets (the study of 3.3.3.4), healthy and not deformities. c. Experimental design: Experiment was completely randomized designed, including four treatments which were 1.5; 3.5; 5.5 and 7.5 individuals/L to equal with 900; 2,100; 3,300 and 4,500 individuals per tank, respectively and repeated three times. The time period of the experiment was 60 days. 8 d. Feed and taking care of: Feed of experiment was pellet which has had 36 % in crude protein. * Feeding and taking care of: Fish was fed by demand, including two times per day at 8 am and 5 pm. * Result records Environmental factors such as temperature, oxy, pH; which were identified by 556 YSI – USA, two times per day. Before arranging experiment, 30 of fry whishker catfish were scaled to indentify the first weigh. When the experiment has finished, most of fish will have scaled by electronic weigh to identify: daily weigh gain (DWG, g/ngày), specific growth rate (SGR, %/ngày) and survival rate. 3.3.3.3. Identify protein requirement of M. bleekeri fingerlings a. Experimental system: Experiment was carried out in the composite system (20 L per tank) in door facility and was aerated continuously. b. Experimental arrangement: Experiment fish which was 269 mg/fish was weaned home-made feed (by the method which has achieved in the best results from experiment 3). Experiment was arranged contingently, including seven treatments, repeated three times with 2.5 fish/L (30 fish per tank) in six weeks. Most treatments have had the levels of protein which were 24%; 29%; 34%; 39%; 44%; 49% and 54%, respectively. c. Food of experiment: Experiment food has had the same of energy (4.36 Kcal/g) and fatty (10 %). Food materials were fish meal, soya bean meal, wheat meal, fish oil, vegetable oil, vitamin – mineral, gelatin and fillers. Table 3.6. Nutritional component of feed Component T 1 T 2 T 3 T 4 T 5 T 6 T 7 Protein (%) 23,94 28,78 33,76 38,94 43,45 48,47 53,73 Lipid (%) 9,38 9,87 9,67 9,63 9,56 9,76 9,84 Carbohydrad (%) 49,0 42,3 35,6 28,8 22,1 15,4 8,72 [...]... was the significantly highest at treatment I (110 ± 9.1 eggs/g female) (p < 0.05) Thus, trash tiny 13 shrimp is an appropriate food for the conditioning process of whisker catfish 4.2 The effectiveness of types and hormone content to artificial whisker catfish reproduction 4.2.1 The effectiveness of hypophysis content to the results of artificial whisker catfish reproduction Table 4.6: The results of. .. Study on the nutritional characteristics of Micronema bleekeri from fry to fngerling Science and Technology Journal of Agriculture and rural Ministry of Agriculture and Rural Development, Vietnam p 58-63 (3) Nguyen Van Trieu, Nguyen Anh Tuan, Duong Nhut Long, 2010 The effects of using different types and doses of hormones on breeding of whisker catfish (Micronema bleekeri) Scientifis Journal of Cantho... (WG) and specific growth rate of whisker catfish which were the highest at treatment VI (49 % of crude protein) were 1,758 mg/fish and 4.81 %/day and were significantly different (p < 0.05) than that other treatments Growth of fish increased gradually from treatment I (24 % of crude protein) to treatment VI (49 % of crude protein) At treatment VII (54 % of crude protein), WG and DWG of whisker catfish. .. calculated mean and standard deviation One-way ANOVA analysis and DUNCAN test were used to compare difference among treatments Data analysis was conducted by using Statistica 5.0 software RESULT AND DISCUSSION 4.1 The conditioning results of whisker catfish maturity 4.1.2 The maturity of whisker catfish 4.1.2.1 The fluctuations of eggs diameter ratio through conditioning process In the first time of May (May... the large sizes was more than cladocera in the 6th day and copepoda in the 20th day 4.3.2 The technological study of whisker catfish rearing from fry to fingerling 4.3.2.1 Experiment 1: The effects of live food to the growth and survival rate of fish b The results of growth in weight of whisker catfish Table 4.9: Weight growth of fish which was reared by live food First weight Weight after 30 DWG SGR... to the other treatments 23 CONCLUSIONS AND RECOMMENDATIONS 5.1 CONCLUSIONS Whisker catfish were maturation cultured in ponds and fed by trash tiny shrimp matured greatly in May and June with gonadosomatic index of females and fecundity of 3.8 ± 0.08 % and 110 ± 9.1 eggs/g female, respectively Vitellogenin content in plasma of fish proportional increased with the development stages of gonad of fish... 30 days, the mean weights and growth of fish at both treatment I and IV which were relatively the highest were 802 ± 1.58 and 782 ± 2.38 mg/fish; 20.3 and 20.2 %/day, respectively, and were not significantly different (p > 0.05) The mean weights and growth of fish at treatment II and III which were lower than that of treatment I and IV have 562 ± 2.56 and 542 ± 1.35 mg; 19.1 và 19.0%/day, and were... whereas the rate of fertilization and hatching were 73.3 ± 6.1 % and 85.4 ± 10.1 %, respectively were higher significantly than that other treatments (table 4.6) 4.2.2 The effectiveness of HCG content to whisker catfish reproduction The results of reproduction by HCG show that fish in all treatments has not yet ovulated After fish was injected by HCG from 6 to 8 hours, eggs of fish were checked and measured... the rates of fertilization and hatching at three treatments were relatively high were not significantly different (p > 0.05) Thus, the stimulation of M bleekeri by Ovaprim at dosage of 0.3 mL/kg female has achieved in high reproduction effects 15 4.3 The study of technological whisker catfish rearing from fry to fingerling 4.3.1 The nutritional characteristics of whisker catfish in fry stage The rate... that protein requuirement of whisker catfish (269 mg/fish) was 43.2 % (figure 4.11) 4.3.5.4 Feed conversion ratio (FCR), Protein effects ratio (PER) and survival rate of whishker catfish Fish fed feeds containing (24 % of crude protein had the highest FCR (2.19), and PCR decreased gradually with the increasing of protein feeds The lowest of FCR was 0.85 at treatment of using 49 % of crude protein PER declined . characteristics and technology of artificial reproduction. The contribution of building the process of whishker catfish reproduction which is: The scientific basis of maturation culture and technology of. MINISTRY OF EDUCATION AND TRAINING CAN THO UNIVERSITY ♣♣♣ NGUYEN VAN TRIEU THE SCIENTIFIC BASIS OF MATURATION CULTURE AND TECHNOLOGY OF WHISKER CATFISH REPRODUCTION (Micronema. whisker catfish. 4.2. The effectiveness of types and hormone content to artificial whisker catfish reproduction 4.2.1. The effectiveness of hypophysis content to the results of artificial whisker