Effects of Starvation and Environmental Temperature on Proximate and Fatty Acid Compositions of Tilapia nilotica

Abstract

Tilapia nilotica which had been kept on a commercial diet supplemented with corn oil were starved for 82 days at different water temperatures (15° and 25°C), and changes in proximate and fatty acid compositions were investigated periodically.
The loss of body weight was more severe in the fish starved at 25°C, together with decrease of protein and lipid contents in the whole body was more marked in the latter. Seven fish died after 82 days of starvation in the water temperature of 15°C, quite different from the result of carp.
Fatty acid distributions in Tilapia lipids were affected to some extent by water temperature during starvation. The percentage of 22:6ω3 increased in the polar lipids of fish starved at the lower water temperature, although the amount of polar lipids in the whole body was almost constant during stravation, not affected by water temperature. The decrease of lipids in the tissue was mainly due to the decrease of triglycerides, but fatty acid composition of triglycerides did not change by starvation at both the temperatures; although in the fish starved for 82 days at the lower water temperature, the percentage of 18:2ω6 decreased. These results suggested that fatty acids utilized for energy during starvation are different from species to species and depend upon environmental temperature.