tailieunhanh - BÁO CÁO " ẢNH HƯỞNG CỦA MẬT ĐỘ ĐẾN TĂNG TRƯỞNG VÀ TỈ LỆ SỐNG CỦA CÁ LÓC BÔNG (CHANNA MICROPELTES) GIAI ĐOẠN BỘT LẾN GIỐNG ƯƠNG TRONG BỂ XI-MĂNG "

The survival rate was highest in the treatment of thinning at the 2 nd week () and significantly different with other treatments (p0,05) và tỉ lệ sống ở 3 mật độ này vẫn khác biệt không có ý nghĩa thống kê (p0,05) cho nên ta có thể ương cá Lóc bông ở mật độ 1200 con/m 2 (tỉ lệ sống là 62,2%) thì đạt hiệu quả hơn 2 mật độ 600 con/m 2 , 900 con/m2 . Giống như trong thí nghiệm trên, cá được san thưa sau 1, 2 và 3 tuần. Khối lượng cá san thưa giữa. | Tạp chí Khoa học 2008 2 11-19 Trường Đại học Cần Thơ ẢNH HƯỞ NG C ỦA MẬ T ĐỘ ĐẾN TĂ NG TR ƯỞ NG VÀ TỈ LỆ SỐNG CỦA CÁ LÓC BÔNg CHANNA MICROPELTES GIAI ĐOẠN Bột L ẾN GIỐ NG ươ NG trong bể XI-MĂ NG Bùi Minh Tâm1 Nguyễn Thanh Phương2 và Dương Nhựt Long1 abstract Giant snakehead Channa micropeltes have been commonly cultured in the Mekong delta. As they are carnivorous cannibalism often appeared to be very high. During the larval stage the bigger sized fish usually hunt for the smaller ones causing high mortality. This study focused on the effects of rearing densities and thinning periods on growth and survival rate of the fry. The first experiment was conducted in concrete tanks for the stage of 0-30 days old without thinning. Growth and survival rate of fish in 3 treatments of 600 900 and 1 200 ind m2 were not significantly different p . Consequently the density of 1 200 tnd m2 62 2 was considered the most effective density compared to 600 con m2 and 900 con m2. Fries were thinned at 1st 2nd and 3rd week. Mean weight of fries thinned at 2nd week was significantly different with those thinned at 1st and 3rd week. The survival rate was highest in the treatment of thinning at the 2nd week and significantly different with other treatments p . Experiment on fish of30-60 days old was designed similarly to the above experiments. For the group of not thinning highest weight of fingerlings was obtained in treatment of 1 200 ind m2 which significantly differed to those stocked at 900 and 600 ind m2. Similar results were obtained for the group of thinning. Highest survival rate was recorded in treatment of1 200 ind m2 and then of 900 ind m2 and 600 ind m2 . However no significant differences were found among treatments. Similar results were also found in the group with thinning. Survival rate of fish thinned at the 2nd week was significant higher than those thinned at the 1st and the 3rd week compared to and respectively . In general