Document Type : Primary Research paper
Unit of Aquaculture
Department of Fisheries and Marine Resources, College of Agriculture, University of Basrah
The current experiment was conducted in earthen ponds at Agricultural Research Station belong to Aquaculture Unit- Agriculture College at Basrah University, Al-Hartha District about 16 km northern-east of Basrah Governorate (30o65`64.6"N, 47o 74`79.5"E) from 17th Feb. to 10th June 2021. Six small earthen ponds (600 m2) were used to investigate the differences of growth criteria for common and grass carp [250 grass carp (T1); 125 grass carp+ 125 common carp (T2); 250 common carp (T3)]. Fishes were fed daily 3% of fish weight on commercial pellets manufactured by Agricultural Consultant Office belonging to Agriculture College using different ingredients (Fishmeal 25%, wheat flour 28%, wheat bran 25%, barley 15%, soya meal 5% and vitamins-minerals premix 2%). 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 food changed after each weighing. Daily feed was divided into three meals, the first given early on the morning, the second at mid-day and the third given at afternoon. Results of current experiment revealed that common carp have good growth criteria compared with grass carp. The best growth criteria recorded by common carp reared with grass carp (T2), where final weight was 898.8 g, weight increment was 663.2 g, daily growth rate was 5.92 g/day and specific growth rate was1.07 %/day. length-weight relationship for the treatments after the end of the experiment illustrated positive allometric pattern of growth for common carp and negative allometric growth pattern for grass carp. The results show little differences in the value of relative and Fulton’s condition factors between before and after the experiment, while there were big difference in the values of modified condition factor before and after the experiment for common carp related to differences in the value of the slope (b).