Hypervitaminosis and safe levels of vitamin A for larval flounder Paralichthys olivaceus fed Artemia nauplii

Abstract

An experiment was designed to identify signs of hypervitaminosis and establish a safe incorporation level of vitamin A (VA) in Artemia nauplii in terms of biological performances and uptake of the vitamin A by larval flounder. Ten-day-old larval flounder were chosen as the experimental fish and cultured for 40 days. Larvae were fed on Tien-tsin strain Artemia enriched in a 10-liter medium containing either 0, 20, 40, 60, and 80 mg or 100 mg VA palmitate (1 μg VA palmitate = 1 IU VA). The enriched Artemia were offered to the larvae till the end of metamorphosis; after that the fish were fed with an artificial diet containing 25 IU VA/g. The VA content of both Artemia and fish was elevated by increasing the VA content of the Artemia culture medium. Feeding Artemia enriched with more than 40 mg VA palmitate produced a negative effect on growth of fish as well as a high incidence of bone deformity. On the other hand, survival of fish was not affected by elevation of VA levels in Artemia, and almost all the fish showed normal body coloration. Thus, excess dietary levels of VA proved detrimental. The safe level of VA in Artemia nauplii was estimated to be less than 50 IU VA/ g on a dry weight basis (20 mg VA palmitate in a 10-liter medium).