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 the market value of the final product. among the nutritional components, phosphorus (p) and calcium (ca) are of special interest as they are directly involved in the development and maintenance of the skeletal system. hence, the present study was carried out to investigate the effects of dietary p and ca on the skeletal deformity, growth and carcass composition the caspian roach ( rutilus rutilus caspicus ) larvae. 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 nah 2 po 4 /kh 2 po 4 . these five diets were supplemented with 1% ca, supplied as caco 3 . 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 larvae and fed three times a day for 60 days. at the end experiment, 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 found between treatments in carcass ash. analysis of length, height and area of vertebrae in two regions of the vertebral column showed no significant difference between the dietary treatments. the skeletal abnormalities were highest incidence in the caspian roach fed with a low p. kyphosis placement of vertebrae was the most frequent abnormality.