Histological study of the Flower horn fish gills (Flower horn) fed different levels of hydrolyzed cow skin

The present study fulfilled to investigate possible changes in the structure of the gills of Flower horn fishes fed diets containing different levels of cow skin hydrolyze. For this purpose, 216 Flower horn fishes with mean weight of 0.95 ± 0.2 g and the mean length of 3.7 ± 0.2 cm were fed for 100 days with levels of 20 percent (T1), 40 percent (T2), 60 percent (T3), 80 percent (T4), 100 percent (T5) replacement hydrolyzed cow skin instead of fish meal. Control diet (T6) had no hydrolyzed cow skin. The results indicated that the gills of fishes fed with level 0, 20 and 40 percent cow skin hydrolyze were healthy and certain symptoms in the gills were not found. In the gills of fishes fed with diet containing 60 percent cow skin hydrolyze, symptoms such as mild hyperplasia in the secondary lamella and mild skin lesions were observed. In some gill tissue samples from treatment (T4) some secondary lamella were wide. In the gill treatment T5, tissue lesions were more. Cutaneous lesions in the secondary lamella, shortage and lengthening of some secondary strings and Aneurysm (hyperemia) in the secondary lamella, were lesions that were observed in the gill tissue samples of treatment T5. From the above findings, it can be concluded that with the increase in cow skin hydrolyze, from levels of 40%, adverse effects in gill tissue was increased.