T. V. R. K. Rao and Arjun Kumar
Effect of some inorganic and organic anions viz., fluoride, silicate, phosphate, malate, tartrate or citrate on aluminium toxicity to an edible fresh water fish, Channa punctatus, has been studied in aquarium models. 10 fish in each case were added to different aquariums consisting of 0.001M Al3+ solutions, along with different inorganic/organic anions (fluoride, silicate, phosphate, malate, tartrate or citrate) in separate sets. One aquarium contained only Al3+ and no other anions. Similar number of fish were also studied in Control set. The fish in all the sets were exposed to toxicity till 60 days or total mortality, whichever was earlier. Mortality of the fish was recorded. At the end, the fish that died last in case of sets where total mortality was observed and surviving fish at 60 days in case of sets in which the fish survived till last, were sacrificed. Five fish of Control set were also sacrificed. Aluminium uptake by the tissue of the fish in different parts viz., head, middle and tail part were studied. Results revealed that the exposure of the fish to aluminium concentration of 0.001M is chronically toxic. 80% of the fish died gradually in 60 days. The upper part of fish (brain and gills) were found to be the major sites of aluminium accumulation. The effect of inorganic and organic anions on aluminium uptake as well as fish mortality were found to be different for different anions. All the anions inhibited the aluminium uptake by the fish tissue as compared to that in aluminium alone exposed set. The inhibition of Al uptake by the anions has been in the range of 59.58 to 84.58%. However, their effect on mortality of the fish were different. Fluoride and malate rather proved to be promoter of mortality as compared to Al3+ alone set. Silicate, phosphate, tartrate and citrate proved to be inhibitors of mortality also. Inhibition of mortality by silicate was found to be 37.5%. Phosphate, tartrate and citrate inhibited Al exposed fish mortality by as high as 87.5%. The results suggest that fluoride and malate might be exhibiting their own toxicity in addition to Al toxicity. Phosphate, tartrate and citrate were found to be good inhibitors of Al uptake by the fish, as well as, their mortality.
