Physiological changes in th blood of common carp (Cyprinus carpio) kept with different densities in biofloc system with acute hypoxia stress

Document Type : Research Paper


1 Department of Fisheries, Faculty of Agriculture and Natural Resources, Gonbad Kavos University, Iran

2 Department of Fisheries, Faculty of Agriculture Sciences and Natural Resources, Gonbad Kavous University

3 Dept. of Fisheries, faculty of Agricultural and Natural Resources, Gonbad Kavous, Iran

4 Department of Biology, Faculty of Science and Engineering , Gonbad-Kavous University, Gonbad, Iran.



Common carp (Cyprinus carpio) with 6, 12, 24 and 48 kg/m3 densities (D1, D2, D3 and D4, respectively, which is an abbreviation of density) were stocked in biofloc environment with acute hypoxia stress in order to investigate the physiological response of fish. At the first stage, the fish were kept in biofloc for 28 days, and then in the second stage of the experiment, the fish were divided separately in 12 tanks with a water volume of 25 liters (4 treatments×3 replicates) with the same biological conditions, and the only variable was the stocking density of fish. Increasing stocking density in D4 treatment (48 kg/m3) significantly increased WBC, RBC, hemoglobin and hematocrit, but decreased lymphocytes and liver enzymes (p< 0.05). Stocking density (6 and 12 k/m3) significantly increased total Ig, lysozyme and ACH50 were observed in D1and D2 (p< 0.05). The stress index had a significant increase in D3 and D4(p< 0.05). Stocking density in D1 and D2 significantly increased SOD and decreased MDA (p< 0.05). In general, it is recommended to control the hypoxia stress in the biofloc environment, the storage density between 6 and 12 kg/m3 so that the problem can be solved within one to two hours.


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