Influence of Nitrates on the Growth of Tillapia and Possibilities for Reducing their Detrimental Effect

D. PAVLOV, Y. STAYKOV, T. MIRCHEVA, J. MITEV and D. DJOUVINOV

Thracian University, Faculty of Veterinary Medicine, BG-6000 Stara Zagora, Bulgaria

Abstract

PAVLOV, D., Y. STAYKOV, T. MIRCHEVA, J. MITEV and D. DJOUVINOV, 1999. Influence of nitrates on the growth of tillapia and possibilities for reducing their detrimental effect. Bulg. J. Agric. Sci., 5: 449-452

A study for establishing the effect of nitrates (200 mg.litre-1 water) on the growth, and nitrate and nitrite concentration in the meat of Tillapia fish was carried out in glass tanks. A mixture from sodium nitrate and potassium nitrate was used as a source of nitrates. One ml of total extract (0.5 %) from artichoke plant (Cynara scolymus L.) was added per litre of water of tanks. One-third part of the water was changed every day but the above-mentioned concentrations of nitrates and artichoke extract were maintained.
Nitrates in the water increased nitrate and nitrite content in the meat and depressed fish growth ability. Supplementation with extract from artichoke plant reduced nitrates and nitrites concentration in the fish meat.

Key words: nitrates, Tilapia fingerlings, growth, artichoke plant, fish meat
Abbreviations: C = head length; D = and body thickness; H = large body height; l = small body length; L = total length; LW = live weight