Comparison of Growth of Common Carp, Cyprinus carpio Cultivated in and outside Cages in Earthen Ponds in Basrah, Iraq

Abstract

The current experiment was conducted in one earthen pond (2500 m2) at Agricultural Research Station of the Aquaculture Unit, College of Agriculture at the University of Basrah, Al-Hartha District from 17 February to 10 June 2021. This experiment aims to investigate growth differences between common carp cultivated in small cages (2 x 3 x 2 meter) located inside earthen pond and those were released in the same pond. Effects of fish stocking density inside small cages were also investigated. Four stocking densities were used [100 fishes in cages 1 and 2 (T1); 150 fishes in cages 3 and 4 (T2); 200 fishes in cages 5 and 6 (T3); 250 fishes in cages 7 and 8 (T4); while 1600 fishes were stocked in the earthen pond (T5)]. Fishes were fed daily 3% of fish weight on commercial sinking pellets manufactured by Agricultural Consultant Office of the College of Agriculture. Total length and weight of fishes were measured at the beginning and at the end of the experiment, while subsamples of fishes were weighed periodically and daily feed changed after each weighing. Daily feed was divided into three meals, the first one was given early at the morning, the second one at mid-day and the third one at afternoon. Results of current experiment revealed best growth criteria in T1 where average final weight was 750.5 g, average weight increment was 454.6 g, average daily growth rate was 4.33 g/day and average feed conversion rate was 2.77. Some of these criteria showed significant differences (P≤0.05) between T1 and other treatments, while feeding conversion rate (3.33) was achieved by fishes reared outside cages in the pond. As a conclusion, it can be pointed out that growth criteria of fishes reared inside cages were better than fishes reared outside cages and fish stocking densities were not affecting growth criteria of fishes reared inside cages.