The three chelating agents. EDTA. Thiamin and Ascorbic acid were tested for balance and tissue distribution of four essential trace elements, copper. Zinc, iron and manganese, blood, liver kidney and muscle in Tilapia florida. Essential trace element balance was less affected by thiamin administration. Thiamin produced minimum alterations in the tissue levels of essential trace elements. Alterations produced by EDTA were more pronounced than those occurred with ascorbic acid and thiamin. Copper, zinc and iron levels in all tissues were drastically depleted by EDTA. The present results suggested that thiamin had the best efficacy as a metal chelating agent.