HYPERVITAMINOSIS AND SAFE LEVELS OF VITAMIN-A FOR LARVAL FLOUNDER (PARALICHTHYS-OLIVACEUS) FED ARTEMIA NAUPLII

An experiment was designed to identify signs of hypervitaminosis and e stablish a safe incorporation level of vitamin A (VA) in Artemia naupl ii in terms of biological performances and uptake of the vitamin A by larval flounder. Ten-day-old larval flounder were chosen as the experi mental fish and cultured for 40 days. Larvae were fed on Tien-tsin str ain Artemia enriched in a 10-liter medium containing either 0, 20, 40, 60, and 80 mg or 100 mg VA palmitate (1 mug VA palmitate = 1 IU VA). The enriched Artemia were offered to the larvae till the end of metamo rphosis; after that the fish were fed with an artificial diet containi ng 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 Arte mia enriched with more than 40 mg VA palmitate produced a negative eff ect on growth of fish as well as a high incidence of bone deformity. O n the other hand, survival of fish was not affected by elevation of VA levels in Artemia, and almost all the fish showed normal body colorat ion. Thus, excess dietary levels of VA proved detrimental. The safe le vel 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).