Effect of oxygen depletion on growth performance of hybrid red tilapia

Abstract

The effect of water oxygen content on growth was evaluated for juveniles Red Hybrid Tilapia, mean ±SD initial weight 1.94 ± 0.27g, reared at oxygen levels of 1, 3 (hypoxia), 5 (normoxia), 7, 10 {hyperoxia) mg.IL with 3 replicates. All 15 tanks were set up randomizely and 20 juveniles were introduced into each tank. Fish were fed to apparent satiation twice per day with a commercial pellet. Dissolved oxygen concentration was achieved by covering tanks with plastic sheets with different measurement depends on different dissolved oxygen concentration. Hypoxic condition (l mg.IL) was achieved by introduced nitrogen gases into completely covered tank, 3 mg.IL was achieved by providing aeration with 2-3 bubbles into uncovered tank, 7 mg.IL was achieved by providing 2 aerations and 10 mg.IL was achieved by introducing saturated oxygen gas into completely covered tank. Feed intake and growth at high DO level were higher than at low DO level perhaps due to higher rate of metabolism. On the other aspect, survival of fish at high DO level was higher than at low DO level. This is due to fish decrease feed intake in order to conserve energy in low DO. In terms of distributions, fishes would station at bottom area in high DO level while distributed at upper area in low DO level.