Impacts of physico-chemical parameters on fish grown under heavy metal stress

The experiment was conducted in glass aquaria to determine the growth potentials of 240-day three fish species viz.,catla catla,labeo rohita and cirrhina mrigala under chronic exposures (1/3 of lc50) of al,as,ba,cr and their mixture (al + as + ba + cr) for 90 days. the growth parameters viz. increase in wet weights,fork and total lengths,feed intake,feed conversion efficiency and condition factor of fish were correlated with physico-chemical parameters viz. total ammonia,dissolved oxygen,carbon dioxide,electrical conductivity,sodium,potassium,calcium and magnesium of the test media (water) of different treatments. the ammonia contents of the test media (water),used for growth trials with three fish species,escalated due to aluminum and arsenic toxicity while it remained lowest in the control media. dissolved oxygen contents of the control media were significantly higher than all other treatments. however,dissolved oxygen contents of water decreased significantly due to arsenic treatment to the fish predicting variable changes in the metabolic rates of fish exposed to either individual metals or metal mixture from that of control. during growth trials,the increase in dissolved oxygen contents of the media used for labeo rohita under chromium stress is indicative of decrease in oxygen consumption by the fish due to onset of acute hypoxia. the average sodium contents of the test media increased significantly due to exposure of labeo rohita to metal mixture. physico-chemical variables like ph,sodium,calcium and dissolved organic matter are known to cause metallic toxicity.