The effect of different temperature manipulations on the performance of koi carp seed was studied to ascertain the optimum life stage-specific temperature for its production. Fifteen glass aquarium tanks were used, featuring four different temperature manipulations (26 °C, 28 °C, 30 °C, and a range from 26 °C to 30 °C), along with a control group with no temperature manipulation. Each setup was replicated three (3) times. Larvae obtained through artificially induced breeding were reared at 100 seeds/tank in different manipulated and non-manipulated temperatures for 120 days. Growth data were collected fortnightly while muscle tissue samples were collected for proximate composition, amino acid, fatty acid, and gene expression analysis.
Growth parameters showed that 30 °C and 26-30 °C produced the best performance and significantly differed (P < 0.05) from other groups after 120 days post-hatching (dph). The linear regression between temperature and specific growth rate displayed a significantly positive linear relationship at 120 dph. Total amino acid was least concentrated at 26 °C, while control and 26-30 °C had substantial differences (P < 0.05) in total essential amino acid. Eicosapentaenoic and docosahexaenoic acids were least concentrated at 26 °C with significant differences (P < 0.05). Total polyunsaturated fatty acid in fish at 30 °C showed a remarkable difference while monounsaturated fatty acid had the highest concentration of all fatty acids detected and was highly concentrated at 26 °C. After 60 dph, the HSP70 gene in fish at 28 °C was influenced by temperature while the MYOD gene in the control significantly differed from fish at 28 °C after 120 dph (P < 0.05).
This study concludes that an optimum specific temperature of 30 °C and fluctuation not exceeding it could be adopted for koi carp seed production.
Keywords: Temperature, growth responses, body composition, genes, Koi carp seed