Effects of fish density on growth and condition factor of grass carp, Ctenopharyngodon idella cultivated in earthen ponds

الملخص EN

The current experiment was conducted in al- Hartha District, about 16 km northeastern Basrah Governorate, during the period 28th February to 26th June 2020.

earthen ponds of the Agricultural Research Station, referring to Aquaculture Unit- Agriculture College-Basrah University, were used to investigate the effects of fish density on growth criteria and condition factor for grass carp, Ctenopharyngodon idella.

The fish were cultivated in six earthen ponds (600 m2 for each one) using three different stocking densities (T1-250 fish in ponds 1 and 2; T2- 500 fish in ponds 3 and 4 and T3- 750 fish in ponds 5 and 6).

The range of fish weight at the beginning of the experiment was 19-203 g, while the range of total length was 12.8-27.0 cm.

Fish were fed daily using commercial pellets manufactured by Agricultural Consultant Office belonging to Agriculture College (fishmeal 20% , soybean meal 20 % , wheat flour 35 % , wheat bran 23 % , and vitamin-minerals premix 2 % ).

Results of the current experiment revealed that the best growth and lowest feed conversion rate achieved by fish reared in T1.

The length-weight relationship proved a negative allometric growth pattern for grass carp cultivated in all stocking densities (b = 2.9702, 2.8140, and 2.7414 for T1, T2, and T3, respectively).

The results showed that the increase of modified condition factor (Kb= 1.15-2.72) with increasing stocking densities, while there was no difference in the range of relative condition factor (Kn = 1.00-1.02) and Fulton's condition factor (K = 1.06-1.20).