Tài liệu Natural food composition in the pond and digestive tract of striped catfish (pangasianodon hypophthalmus) during nursery stage

CAN THO UNIVERSITY COLLEGE OF AQUACULTURE AND FISHERIES NATURAL FOOD COMPOSITION IN THE POND AND DIGESTIVE TRACT OF STRIPED CATFISH (Pangasianodon hypophthalmus) DURING NURSERY STAGE By NGUYEN LAM PHUONG NGOC 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 FISHE RIES NATURAL FOOD COMPOSITION IN THE POND AND IN THE DIGESTIVE TRACT OF STRIPED CATFISH (Pangasianodon hypophthalmus) DURING NURSERY STAGE By NGUYEN LAM PHUONG NGOC A thesis submitted in partial fulfillment of the requirements for the degree of Bachelor of Aquaculture Science Supervisor Assoc. Prof. Dr. VU NGOC UT Can Tho, December 2013 APPROVEMENT The thesis “Natural food composition in the pond and digestive tract of Striped Catfish (Pangasianodon hypophthalmus) during nursery stage” defended by Nguyen Lam Phuong Ngoc, which was edited and passed by committee on December 27 th, 2013. Sign of Supervisor Assoc. Prof. Dr Vu Ngoc Ut Sign of Student Nguyen Lam Phuong Ngoc ACKNOWLEDGEMENT First of all, I want to express my special thanks to my supervisor, Associate Professor Dr. Vu Ngoc Ut for being invaluable guidance, advice, and encouragement to my thesis completion. Many thanks are also given to all other teachers of the College of Aquaculture and Fisheries, and especially to those of the Department of Applied Hydrobiology for providing me with great working and learning conditions. I would love to express my sincere appreciation to miss Nguyen Hong Linh, master student of Aquaculture Course 19 for her unconditionally kind help throughout the experimental period. Last but not least, I really want to thank my academic adviser, Dr. Duong Thuy Yen, who was guiding and encouraging me over the last four years, and my family, my friends in Advance Aquaculture Class Course 35 for their great lifetime support which makes everything possible for me. Nguyen Lam Phuong Ngoc i ABSTRACT Study on natural food composition in the pond and in the digestive tract of Stripped Catfish (Pangasianodon hypophthalmus) during nursery stage served as base for improving and enhancing survival rate of fry stage. The study was carried out in Tien Thuy – Chau Thanh Hatchery of Ben Tre Seafood Import – Export Joint Stock Company during 28 nursery days; fifteen days collected sample in three nursery ponds. The samples were collected a day before stocking fish, everyday in the first week and three day intervals. The result obtained in nursery ponds showed that there were 140 species of zooplankton including 36 species of Protozoa, 56 species of Rotifera, 17 species of Cladocera, 30 species of Copepoda and Nauplii. In the water supply canal, 16 species of zooplankton were recorded includeding 5 species of Protozoa, 6 species of Rotifera, 3 species of Cladocera, 2 species of Copepoda and Nauplii. The density of zooplankton in the pond varied from 5,889 to 4,680,000 inds/m3 and in the water supply canal varied from 2,778 to 250,000 inds/m3. In the digestive tract of the fry, 4 zooplankton groups were found. Rotifera accounted for 5.16%, Protozoa 0.15%, Cladocera 68.29%, Copepoda 24.15% and Nauplii 0.83%. Result from natural food in the digestive tract indicated that Cladocera was the most favorite food of Stripped Catfish in first seven days after stocking and during nursery stage. These results showed the abundant food selection of Stripped Catfish fry in nursery pond with many different natural food compositions. Keywords: Zooplankton, nursery stage, digestive tract. ii TABLE OF CONTENTS ACKNOWLEDGEMENT ............................................................................. i ABSTRACT ................................................................................................. ii TABLE OF CONTENTS ............................................................................ iii LIST OF FIGURES .......................................................................................v LIST OF TABLES ...................................................................................... vi LIST OF ABBREVIATIONS..................................................................... vii CHAPTER 1 INTRODUCTION ...................................................................1 1.1 Background of study .............................................................................1 1.2 Research objectives ..............................................................................2 1.3 Research contents .................................................................................2 CHAPTER 2 LITERATURE REVIEW ....................................................... 3 2.1 Situation of Striped Catfish seed production in the Mekong delta ...... 3 2.2 Biological characteristics of Striped Catfish ........................................4 2.2.1 Classification ..............................................................................4 2.2.2 Distribution .................................................................................4 2.2.3 Morphological characteristics .....................................................5 2.2.4 Nutritional characteristics ...........................................................5 2.2.5 Growth characteristics.................................................................6 2.2.6 Reproductive characteristics........................................................6 2.3 The role of natural food in aquaculture ................................................7 2.3.1 Rotifer ....................................................................................... 8 2.3.2 Copepoda ..................................................................................10 2.3.3 Cladocera ..................................................................................12 CHAPTER 3 METHODOLOGY ................................................................ 14 3.1 Location ............................................................................................14 3.2 Time ..................................................................................................14 3.3 Equipments ........................................................................................14 3.4 Sampling method ...............................................................................14 3.4.1 Fish specimens ..........................................................................14 3.4.2 Zooplankton sampling............................................................... 14 iii 3.4.2.1 Qualitative analysis .......................................................15 3.4.2.2 Quantitative analysis .....................................................15 3.5 Sample analysing method ..................................................................15 3.5.1 Zooplankton analysis ................................................................ 15 3.5.1.1 Qualitative analysis .......................................................15 3.5.1.2 Quantitative analysis .....................................................15 3.5.2 Fish sampling analysis .............................................................. 16 3.6 The method for data analysis ............................................................. 18 CHAPTER 4 RESULTS AND DISCUSSION ............................................19 4.1 Zooplankton species composition .....................................................19 4.1.1 Zooplankton composition in nursery ponds ................................ 19 4.1.2 Zooplankton composition the water supply canal ........................19 4.2 The density of zooplankton composition ...........................................20 4.2.1 The density of zooplankton composition in nursery ponds ..........20 4.2.2 The density of zooplankton composition in the water supply cannal ..........................................................................................................23 4.3 The zooplankton size in nursery pond ................................................24 4.4 Mouth gap size of Striped Catfish in nursery stage ............................24 4.5 Natural food composition in the digestive tract in 28 nursery days....26 4.5.1 Frequency of food composition in digestive tract ......................26 4.5.2 Point counting of food composition in digestive tract ................27 4.5.3 Combination point counting with frequency of food composition in digestive tract ......................................................................25 4.5.4 Coefficiency of food choice of Striped Catfish in 28 nursery days .........................................................................................................29 CHAPTER 5 CONCLUSIONS AND RECOMMENDATION ....................30 5.1 Conclusions .......................................................................................30 5.2 Recommendation ...............................................................................30 REFERENCES............................................................................................31 APPENDICES ............................................................................................34 iv LIST OF FIGURES Figure 2.1 The external image of Striped Catfish Figure 2.2 Some species of rotifer Figure 2.3 Some species of copepod Figure 2.4 Some species of cladocera Figure 4.1 The percentage of zooplankton species groups in nursery pond Figure 4.2 The percentage of zooplankton species groups in the water supply canal Figure 4.3 The density of zooplankton (inds/m3) in nursery pond Figure 4.4 The density of zooplankton (inds/m3) in the water supply canal Figure 4.5 Mouth gap size of Stripped Catfish fry (µm) in 28 nursery days v LIST OF TABLES Table 4.1 Mouth gap size of Striped Catfish in 3 nursery ponds Table 4.2 Frequency (%) and the rate (%) of food composition in digestive tract with age Table 4.3 Analysing result of point counting of food composition in digestive tract in 28 nursery stage Table 4.4 Analysing result of food composition in digestive tract by combination point counting with frequency Table 4.5 Coefficiency of food choice of fry in 28 nursery days v LIST OF ABBREVIATIONS µm Micrometer Fig Figure Inds Individuals Kg Kilogram Min Minimum Max Maximum v CHAPTER 1 INTRODUCTION 1.1 Background of study In recent years, aquaculture has been developed rapidly around the world. Especially in Vietnam, the movement of culturing Striped Catfish has developed exceeding planning production. Aquaculture provided 52% of production and more than 60% value of exports in which Striped Catfish reached high number of export turn over. Mekong Delta has the advantages for culturing Striped Catfish. Can Tho, An Giang, Dong Thap provinces provide large seed resources for aquaculture processing factory. In 2012, the total production of Striped Catfish in the region reached nearly 4.6 billion (increased nearly 2 times compared with 2011). According to Directorate of Fisheries Statistics 2012, the region exported 53,000 tons of catfish, raised the total amount of fish exported to 592,000 tons, valued at $1.6 billion. Compared with 2011, the area of cultured pond increased 11.6% (5,300ha) but the total value of exports fell by 2.2% due to Tra catfish price reduced from 0.2 to 0.4 USD / kg. Besides, catfish industry must be facing with difficulties due to the shorten of materials. Commercial fish farming reach high efficiency depends on many factors, the quality of fingerling is one of the decisive factors. Fingerlings are the important factor to help improve the quality as well as production of Striped Catfish, at the same time; it increases profits and minimizes risks for farmers. However, the quality of seed is decreasing because famers have not cared about fingerling quality. In fingerling production, food and feeding technique are very important in nursing fish. Today, although there are many advanced techniques in the artificial food production for larvae, but live food such as algae, rotifers, crustaceans, artemia are still considered very important and have great potential in the seed production. One of matters need special interest is shorten of natural food in nursery stage. In fry stage, mouth size of larvae is small, the sensory organs as eyes, touch, lateral line organs have not developed fully and the digestive system is not complete; so limiting the selection and proper use of feed during starting eating outside (Vu Ngoc Ut, 2012). In nursery stage, natural food plays an important role in growth and survival rate. Natural food is the most favorite food of fish in stage from fry to fingerling. Natural food compositions 1 affect to survival rate and fry quality in the pond. Especially, natural food provides essential nutrient for larvae. Although there have been much researches on the composition of fish food during nursery stage, they still are not complete. This problem needs more investigable research in order to ensure the survival and growth rate of fish. The experiments on “Natural food composition in the pond and digestive tract of Striped Catfish (Pangasianodon hypophthalmus) during nursery stage” will identify natural food ingredients for nursery stage. Besides, it provides some information about the efficiency of natural food in aquaculture. 1.2 Research objectives To investigate the composition of natural food in the ponds and digestive tract of striped catfish during the nursery stage to serve as base for providing appropriate feeding regimes to improve survival rate of fish fingerlings. 1.3 Research contents - Investigation on natural food composition (zooplankton) in the pond during the nursery period. - Investigation of natural food composition in the digestive tract of fish during the nursery period. 2 CHAPTER 2 LITERATURE REVIEW 2.1 Status of Striped Catfish seed production in the Mekong Delta Mekong Delta is one of seven important economic regions of Vietnam. Nature area is approximate 4 million hectare, about 12% total area of the country (Directorate of Fisheries Statistics, 2009). From the first half of the 20th century, catfish farming in ponds began to practice in the Mekong River Delta and had contributed to provisions for people. But in the dry season, the amount of fish in the river was decreasing due to the fry river; fish was pulled out of the sunken field so fish provided for market was scarce. Due to before 1970 fishery was restricted culturing techniques and fingerlings, most Striped Catfish broodstock resources completely depended on nature. From the 1980s, Mekong Delta had just begun to research and successed in Striped Catfish artificial breeding after more than 30 years of natural breeding dependence. However, until 1990s, farmers had just used widely fingerlings. Especially, from 1999 to now, fingerlings supplied all Striped cultured sources with an average output of 1.5 - 2 billion fish/ year. From only a few households until now the whole area had 5,775 breeding households (Pham Van Khanh, 2006). Thence, fry nursery industry began to develop and concentrated mainly in the region as Tan Chau, Chau Doc, Hong Ngu, islands on Tien river as Long Khanh, Phu Thuan. Early 1990s, fry yield catched anually reached only 150 – 200 million fries (Vuong Hoc Vinh, 1994). Nowaday, the demand of Tra fingerling is about 1.8 to 2.4 billion fries every year. Mekong Delta has about 200 breeding hatcheries and 4000 households nursing fry on the density more than 2,500 ha with total productivity is more than 2 billion fingerlings, fry productivity in region meet livestock demand (Ministry of Agriculture and Rural Development, 2012). In particular, provinces produce many Striped Catfish fry are Dong Thap, Can Tho, and provinces have many nursing hatcheries are Can Tho, An Giang, Dong Thap and Tien Giang. However, due to the unstable fish material market that makes farmers feel less secure to invest in production. Many households are not interested in seed quality, production and business conditions do not also ensure regulations. Thereby it causes loss in the rearing; the loss ratio exceeds 30% of the number of fish stocked. 3 2.2 Biological characteristics of Striped Catfish (Pangasianodon hypophthalmus) 2.2.1 Classification Phylum Chordata Subphylum Vertebrata Class Actinopterygii Order Siluriformes Familia Pangasiidae Genus Pangasianodon Species Pangasianodon hypophthalmus Figure 2.1 The external image of Striped Catfish 2.2.2 Distribution Striped Catfish distribute in Mekong River Basin, present in all four countries Vietnam, Laos, Cambodia and Thailand. In Vietnam, many years ago, when there was no artificial broodstock, fry and fingerling, they were usually captured on Hau and Tien River. Mature fish only found in the ponds, rarely in the wild region of Vietnam, due to fish migrated up Mekong River to live and find out where natural reproduction. 4 2.2.3 Morphological characteristics Trương Thu Khoa and Tran Thi Thu Huong (1993) described Striped Catfish as: - Head large, flattened; mouth short, looked from the top to the tip the mouthround. - Terminal mouth, horizontal width, no stretch, arch shape and located on the horizontal plane. - Teeth small, smooth; palate teeth are divided into 4 small, slim patches - Two barbels; extending maxillary barbel not beyond a vertical pectoral fin margin; mandibular barbel shorter. - Posterior naris closer anterior naris than eyes and in a straight line drawn from the nose to the edge of the eye holes. - Body elongate; lateral part flat; lateral line complete, branch, starting from gill margin to the middle of caudal fin. fin. - The back of the spine of dorsal fin, pectoral fin serrate down the caudal Pelvic fin extending not touch posterior point of anal fin. - In large fish, the back of body and head blue gray or brown black and pale down abdomen, abdomen silver white. - Pelvic fin and anal fin yellow. 2.2.4 Nutritional characteristics After finishing the yolk sac, fry fish begin to use external food such as rotifer, waterflea... The common food of fingerling is not larger than the diameter of the eyes, but for Striped Catfish, preys that they catch are much larger than the diameter of their eyes (Pham Van Khanh, 2006). Artemia lavae give high survival rate and best growth (Duong Thuy Yen, 2003). Striped catfish is omnivorous but they have inclining to eat animals, food from animals will help fish grow faster. In nature, fish eats organic humus, aquatic roots, vegetable, shrimp, crab, insects, snail and fish. Fish in culture pond can use different food as trash fish, pellets, bran, groat, spinach,... (Duong Nhut Long, 2004) 5 2.2.5 Growth characteristics Striped catfish grows very fast, small fish grows length fast, fish reaches 10 – 12 cm length, 14 – 15g weight in 2 months age. Fish grow quickly from year 1 to year 3. After one year, the average weight is about 1kg/fish. After two year, fish reaches from 3 to 3.5kg/fish. Male fish grows faster than female fish (Tran Van Vy, 2005). Fulton fat of fish increases gradually with the weight and the fastest in the early years, males often has a higher fat and they usually decrease as the breeding season. (Nguyen Chung, 2007). 2.2.6 Reproductive characteristics In nature, reproductive season of Striped Catfish starts from May to July yearly. Striped Catfish does not breed in culture pond. In Vietnam, Striped Catfish does not breed ground in nature. Fish breed in Cambodia, fry will be along the stream to Vietnam (Duong Nhut Long, 2004) In artificial breeding, Striped Catfish can be raised early maturation and spawned sooner than in wild, normally in March. Spawning in wild will not get re-development state. But in artificial breeding condition, Striped Catfish can be re-reproductive 1-2 times in year (Pham Van Khanh, 2006). 6 2.3 The roles of natural food in aquaculture Natural foods are phytoplankton or zooplankton, benthic animals, microorganisms, organic waste humus. Natural foods have many advantages such as small size, suitable for larval mouth size, contain a large amount of free amino acid, the peptic single circuit, unsaturated fatty acid polymer, which contain natural enzyme system can resolve, which provide a full range of nutrients especially for aquatic animals (Tran Thi Thanh Hien and Nguyen Anh Tuan, 2009) Fish is able to live and develop in the environment not meet the full range of essential nutrients and especially small fish. In the larval stage, fish use completely food from the outside; while the morphology can change a lot, unstable, individual have to find food to survive when the body is too weak. So food plays an important role in the existence and development (Pham Minh Thanh and Nguyen Van Kiem, 2009). Plankton is the natural food source of the larval stages of many aquaculture species. The use of live feed in larval rearing therefore remains a necessity in most aquatic organism hatcheries. In fact, most early stages of fish larvae do not react to dry feeds and require live feeds that swim actively and stimulate their omnivorous behaviour. In addition, larval fish usually do not ingest or are not able to ingest formulated feeds (Guillaume Drillet, 2012). In biology, zooplanktons are the second important link behind algae in the natural chain, are direct or indirect food for shrimp and fish, especially in larval stage. The development of zooplankton in basin affects to the development of other species (Tran Suong Ngoc, 2009) 7 2.3.1 Rotifer In classification system of Pechenik (2000), rotifer is determined as Phylum: Rotifera Class: Monogononta Order: Ploima Family: Brachionidae Genus: Brachionus Species: Brachionus angularis (Gosse, 1851) Brachionus plicatilis (Muller) Figure 2.2: Some species of rotifer Rotifers are small, mostly freshwater animals, and are amongst the smallest members of the Metazoa that group of multicellular animals which includes humans, and whose bodies are organized into systems of organs. Most of rotifers are about 0.5mm in length or less, and their bodies have a total of around a thousand cells. This means that their organ systems are a greatly simplified distillation of the organ systems found in the bodies of the higher animals (Herbert Dartnall, 1978). In culturing Dwarf Gourami larvae, the rotifers used as starter food significantly improved the growth and survival of Dwarf Gourami larvae (Day 2 – 12). The use of rotifers would enable freshwater larviculture to improve larval performance, increase yield, and facilitate breeding of new fish species with small larvae (Lim L.C, Wong C.C, 1997). After hatching 45 hours, Micronema bleeker start to nutrient outside. Analysing of digestive organ of fish show that Copepoda larvae and rotifer are the most abundant food in the digestive system of Micronema bleeke. It 8 suggests that fish begin eating zooplankton when they start eating outside (Nguyen Van Trieu, et al., 2008). Among the 13 species of Brachionus recorded during the present study, B. angularis was the smallest in size. The smallest size and its shape may enable them to be used as suitable live feed for the larvae having small mouth opening, which in turn may lead to higher survival rate and enhanced fish production (Molly Varghese, 2006). In study about the potential competition and feeding impact of the common rotifer species, Keratella cochlearis and K. quadrata, on the abundant prostomatid ciliates, Urotricha furcata and Balanion planctonicum, in laboratory batch culture experiments. All four species have similar feeding preferences, co-occur in many freshwater environments, and are thus potential competitors for the same algal food. Two small Cryptomonas species served as food for the ciliates and the rotifers in the experiments. Growth rates of each ciliate species were measured when they grew alone and when they were paired with one of the rotifer species. Both rotifer species reduced the growth rate of U. furcata, probably primarily by direct feeding on the ciliates. Growth rate of B. planctonicum was unaffected by K. cochlearis, but was drastically reduced by grazing and/or mechanical interference of K. quadrata. These results suggest niche partitioning of the sympatric ciliates with respect to their rotifer predators (Thomas Weisse, 2001). In investigation about distribution of freshwater rotifer Brachionus angularis in Hau river estuary and Can Tho-Hau Giang, in freshwater ecosystem Brachionus angularis was discovered in flow-water ecosystem as river or small irrigation canal from 433 to 1,111 ind/m3 (around 5.2 to 17.7% B. angularis/total of rotifers). In low pH water from 4 to 6; B. angularis appeared in rice-field, ponds with density from 3700 to 31,050 inds/m3 and 2.9 to 6.6% B. angularis/total of rotifers. They were discovered in Hau river estuary with low salinity (from 1 to 5‰) but no detection in tiger shrimp pond in high salinity (fron 10 to 15‰) (Tran Suong Ngoc, 2009) 9 2.3.2 Copepoda Figure 2.3 Some species of copepod Copepods play major role in pond ecosystem, serving as food for small fish, micropredators of fish and other organisms, fish parasite, intermediate hosts of fish parasites and hosts and vectors of human disease. Plankton animals, especially rotifers, cladocerans and copapods of the order Cyclopoida are the most important food items in freshwater aquaculture and copepod nauplii are especially valuable for feeding fry. Copapods used as natural food are either cultured of collected from natural water bodies (Wojciech Piasecki, 2004). Reports by Fryer (1957) indicate that Cyclops viridis is predatory; among 51 guts examined he found approximately 22% with oligochaetes, 18% with cyclopoid copepods, 16% with dipteran larvae, and 6% with cladocerans. These figures suggest that the results obtained with Cyclops viridis and Simocephalus vetulus may have been atypical since the copepods were forced to exist on an unnatural diet. Another possibility is that not all of animals used were Cyclops viridis since only a few were sent away for taxonomy verification. In some areas of Truong Sa Archipelago, study about natural food sources serving aquaculture, zooplankton has variable species (81 species), in which Copepoda has 41 species, accounting for 50.62% with average density 11,775 ind/m3. The density of zooplankton is high in some islands as Sinh Ton, Thuyen Chai, Truong Sa. They are a good food source for shrimp and fish (Nguyen Minh Nien, et al., 2012) Through a study about assessing biodiversity and spatial of zooplankton communities in the Cu Lao Dung mangrove ecosystem in Soc Trang province, structure of species composition is different, in dry season and rainy season, the density of Copepoda and nauplius larvae are dominant with the ratio 70 10