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Bài báo - Tạp chí
(2015) Trang: 57
Tạp chí: IFS 2015
Liên kết:

Striped catfish (Pangasianodon hypophthalmus, Sauvage, 1878) is one of the most important exported products of Vietnam. Currently, survival rate of striped catfish during nursery stage is too low. Therefore, one of the most interested issues is to find out technical solutions to improve and enhance the survival rate of fish during nursery stage.The practical experiment was carried out in 9 nursery ponds (pond size from 1.500 m2 to 3.600 m2/pond) with 3 different nursing densities(Treatment I: 600 larvae/m2; Treatment II: 800 larvae/m2 and Treatment III: 1000 larvae/m2) in two months at theCenter for applied science and technology of Caseamex company and Phu Thuan farm of Thuan Hung company. After two months of nursing from larvae to fingerlings in earth ponds, the experimental results indicated that water quality parameters showed in acceptable ranges for the larvae of catfish growth during the sampling  period. The DO concentration in three practical experiments (T. I; T. II; T. III) were 6,78±1,48 mg/L, 6,56±1,47 mg/L and 3,94±4,3 mg/L respectively. The TSS concentration fluctuated between 23±14 - 42±16,1 mg/L. The ammonium (N-NH4+) concentration in three experiments (T. I; T. II; T. III) were 0,39±0,17 mg/L; 0,36±0,17 mg/L and 0,52±0,45 mg/L respectively.  The ammonia (NH3) fluctuated value between 0,024±0,025 mg/L and 0,054±0,053 mg/L. The Phytoplankton composition in larvae nursing ponds was found 68 species, and the densities ranges from75.620-246.592 cell/L in which the species of chlorophyta was dominant group. The zooplankton composition included 48 species in nursing ponds and the densitiesof phytoplankton fluctuated from 4.116- 128.990 inds/L.The analytical results showed that there were four zooplankton groups distribution in digestive tract included rotifera, cladocera, copepoda, and nauplii in which rotifer group was the most importantnatural food for catfish larvae’s in 3 days of the nursing stage. The length and the weight of treatment I of 12,49±1,89cm; 7,25±3,64g/fish and treatment II of 12,3±1,58 cm; 7,17±3,56g/fish were higher than those of treatment III. The survival rates of treatment I of 19% was higher than those of treatment II of 16% and treatment III of 8%.

 


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