Abstract

During the late summer and early Fall of 1998, commercial producers of ornamental livebearers in Florida reported that high percentages of harvested fish had severe scolisis and were consequently non-saleable for aesthetic reasons. Clinical evaluation of affected fish revealed no evidence of infectious etiology. Preliminary assessment indicated that scoliosis was the result of dietary ascorbic acid deficiency. A dietary study was run in which swordtail fry were fed manufactured diets with the following concentrations of ascorbic acid: 0, 60, 300 and 3,000 mg/L. The study was run at 24 and 32°C, respectively. Fish were maintained on the study for approximately ten weeks. Results indicated that gross visible scoliosis did not develop in any treatment group when fish were reared at 24°C, but deformed fish were present in all treatment groups when reared at 32°C. Results of this study indicate that water temperature may influence the development of scoliosis in juvenile swordtails. Whether higher water temperature increases the ascorbic acid requirement of these fish is not clear.

Acknowledgements

This work was supported by a grant from the Florida Tropical Fish Farms Association. Test diets were manufactured and provided by Purina Mills (St. Louis, MO).