Dry diet-influenced growth, size variability, condition and body deformities in juvenile crucian carp Carassius carassius L. reared under controlled conditions

The growth, size variability, condition coefficient and percentage of fish with external deformities were compared in juvenile crucian carp (initially 31 mm TL and 0.36 g BW) which were fed intensively four starters only for 120 days at 25°C. The best weight gain was achieved by fish fed an experimental carp diet with the lowest fat content (7.4%) and a commercial diet for eel containing 15.9% fat (4.33 and 4.15 g BW, respectively). In contrast to the experimental diets, both commercial diets produced fish with high condition coefficient values and a very high (37.2 or 62.7%) percentage of individuals with different external deformities. Size variability did increase over the course of the experiment except in the fish fed the high-energy diet for eel. Survival rates ranged between 96.5 and 99.5%. Our results indicate that juvenile crucian carp can be successfully reared exclusively on dry diets but not the commercial ones for eel or carp used in the present experiment.