Effect of Varying Dietary Protein Sources on Growth and Spawning Performance and Gonad Maturation of Red Tilapia Reard in Sea Water

Abstract

Four-week-old Red tilapia fry with an average weight of 1.9 g were reared in saline water (36%) for 190 days on 6 formulated iscaloric diet of protein level (28%). The experiment was conducted in glass aquaria. Six diets were formulated including a control diet based on fish meal (diet 1) and fish silage (diet 2) and soybean (diet 3). The other 3 based diets supplemented with 35% fish meal and 60% fish silage (diet 4), 35% fish meal +65% soybean diet (5) and 50% fish silage +50% soybean (diet 6). There were six treatments in duplicates. The results indicate that supplementation with 65% fish silage let to a significant (p<0.05) growth performance (final weight gain 152.2 +/- 1.1 g, SGR 1.08 and daily gain 0.80 +/- 0.06 g day(-1)) and efficient feed utilization (FCR 1.9, PER 2) comparable to other diets. Complete replacement with soybean resulted a significant (p>0.05) low growth performance (weight gain 2.43 +/- 0.06 g, SGR 0.65 and 0.41 +/- 0.01 g daily weight gain) and less efficient in feed utilization (FCR 2.9 and PER 1.2). The present study also investigated the reproductive performance of red tilapia in sea water. The six diets were fed to red tilapia fries. The first spawning of the brood stock of fish groups occurred at almost the same age. There was a significant (p<0.05) difference in the absolute fecundity fertilization and hatching rate of fertilized eggs among fish fed soybean and the other diets. While no significant difference in the spawning intervals, gonad maturation, egg size, were resulted.