Studies on water soluble vitamin requirements in Cichlasoma urophthalmus (Gunther 1862)

Abstract

Recently, studies on the Mexican native cichlid Cichlasoma urophthalmus, have shown it to be a strong candidate for culture in the region, but work on its nutritional requirements is lacking.

In this study the qualitative requirements for the eleven water soluble vitamins were determined. Three experiments were carried out to determine the quantitative requirements of vitamin C, pyridoxine and calcium pantothenate for C. urophthalmus, based on growth response, food conversion ratio, histopathological changes and mortality.

It was demonstrated that C. urophthalmus requires at least 9 of the eleven essential water soluble vitamins: pyridoxine, pantothenic acid, vitamin C, riboflavin, biotin, niacin, thiamin, choline and inositol. Folic acid and cyanocobalamin did not affect performance of fish in short term experiments.

C. uroohthalmus required 40mg of ascorbic acid/Kg diet for normal growth and 11Omg/Kg diet to prevent deficiency signs. Fish fed vitamin C deficient diets developed anorexia, reduced growth, haemorrahges, exophthalmus, lordosis, short operculae, loss of scales, erosion of skin and fins as external signs of deficiency. Histologically they suffered severe gill and bona changes, muscle atrophy, necrosis of the hepatocytes and pancreas. In addition various pathological abnormalities in the ganglion cells ware reported for the first time in fish fad a vitamin C deficient diet. Fish tuberculosis was present in the fish fed vitamin C deficient diets, and it is concluded that adequate levels of vitamin C help prevent Mycobacterium infection.

C. urophthalmus fry were found to require 5rmg of pyridoxine/Kg diet for normal growth and health, and when fed a pyridoxine deficient diet showed the commonly described deficiency signs of loss of appetite, retarded growth, lethargy, rapid breathing, nervous disorders and high mortality. There were no histological signs of deficiency probably due to the early cessation of growth and rapid mortality. An overdose of pyridoxine did not cause toxicity or reduced growth.

Diets for C. urophthalmus had to bo supplemented with at least 80 mg of calcium pantothenate/Kg diet to achieve maximum growth and food conversion ratios and to avoid external and histological deficiency signs. C. urophthalmus showed anorexia, reduced growth, fin and skin haemorrhages and high mortalities as external signs of deficiency of this vitamin and practical dietary levels of 120 to 160 mg/Kg are recommended. The histological changes noted ware clubbed gills, necrosis of the pancreas and glycogen deposition. Hepatic ceroidosis due to calcium pantothenate deficiency was reported here for the first time.

The data are discussed in relation to those available for other fish species.