The skeletal deformity in response of dietary phosphorus and calcium level in the Caspian roach (Rutilus rutilus caspicus) larvae

Skeletal deformities are a common problem in fish hatcheries and commercial farms that affect growth, development and survival as well as market value of the final product. Among the nutritional components suspected to affect skeletal deformities, phosphorus (P) and calcium (Ca) are of special interest as these key minerals are directly involved in the development and maintenance of the skeletal system. The present study was carried out on the Caspian roach (Rutilus rutilus caspicus) larvae to investigate the effects of dietary P and Ca on the skeletal deformity, growth and carcass composition. In this study six semi-purified diets were formulated. The diets A, B, C, D and E were supplemented with 0.0, 0.4, 0.8, 1.2 and 1.6% available P supplied as a 1:1mixture of NaH2Po4/KH2Po4. These five diets were supplemented with 1% Ca supplied as CaCo3. Diets F was Ca-free and supplemented with 0.8% available P served as control level of P. Each diet was randomly assigned to triplicate groups of fish and each group was stocked with 30 fish larvae and fed 3 times a day for 60 days. At the end of feeding trial there was no significant effect of dietary P (0 to 1.6%) or Ca (0 or 1%) supplementation on growth performance such as weight gain and FCR, carcass moisture, P and Ca. However, a significant difference between treatments in carcass ash. Analysis of length, height and area of vertebrae in 2 regions of the vertebral column detected no significant difference among the dietary groups. The skeletal abnormalities were highest incidence in the Caspian roach fed with a low P. Kyphosis placement of vertebrae was the most frequent abnormality.