Acute toxicity bioassay of three different heavy metals copper (Cu), lead (Pb) and cadmium (Cd) for the freshwater catfish, Clarias batrachus were conducted for evaluation of the toxicity. The 96h LC 50 values recorded for Cu, Pb and Cd were 15 ppm, 29 ppm and 35 ppm respectively. The results of this study indicate that the order of toxicity of these heavy metals is Cu>Pb>Cd in short duration acute toxicity experiments. The toxicity was found to be dependent on dose and duration of experiment for all these heavy metals. Cu was found to be much more toxic than Pb and Cd to C. batrachus.

The main objective of this study was to evaluate the acute toxicity of raw, neutralized and physicochemically treated and biologically treated effluent of herbal pharmaceutical industry. The acute toxicity test was determined using freshwater crustacean Ceriodaphnia dubia under laboratory conditions. LC 50 values for raw, neutralized and physico-chemically treated effluent for 12, 24, 36 and 48 h ranged between 3.0-4.5%, 3.9-10.8% and 22-28% respectively. It is evident from the results that physicochemical treatment reduced the toxicity by around 25% while biological treatment reduced the toxicity completely. Results subjected to statistical evaluation depicted regression coefficient of more than 0.9 indicating good correlation between the mortality rate and effluent concentrations.

In India a large number of pharmaceutical industries are manufacturing drugs of complex type subsequently producing huge quantities of wastewaters. The herbal pharmaceutical industries are one of them which manufacture various herbal medicines from natural products and certain chemicals and metal combinations. During their manufacturing process a large number of toxicants enter the watercourse harming the biota of the receiving water bodies. Zooplankton organisms being at the base of the food chain if affected, will subsequently affect the fisheries potential at large, harming the interest of man. Keeping this point in view a herbal pharmaceutical manufacturing industry based at Nagpur was selected for investigation with respect to assessing its toxic effect on the freshwater crustacean Cypris spp. during short duration toxicity tests. This research paper discusses in detail the bioassay evaluation of raw, neutralized and physico-chemically treated herbal pharmaceutical effluent for arriving at a concentration safe for the Cypris spp.

The  zooplankton occupy  a central  position   between  the  autotrophs  and  heterotrophs  and  form  an important link  in  the  food  chain  of a freshwater ecosystem.  The  occurrence and  abundance of zo0plankton  is  always  influenced  by physico-chemical  factors  and the  level  of nutrients  present  in the water body.  In this  context  a perennial  freshwater  reservoir  Wadgaon  dam is studied  with respect to zooplankton population to assess  the  types  of zooplankton present.  Qualitative  studies on  the zooplankton in the  Wadgaon  dam  reservoir situated  in  the  Nagpur district  were  undertaken  in monsoon  months   to assess  the extent  of forms  present. The  reservoir  water  is uncontaminated  and clean  with no  influence  of man  made  activities   in the  vicinity.  The  zooplankton population   of the reservoir  water  is found to be represented  by fie different groups  viz. Protozoa, Rotifera, Cladocera, Copepoda  and  Ostracoda  represented   by about  21  different forms.  The  present  study  indicate the uncontaminated  nature   of reservoir water  due  to  absence of pollution  indicator  species  in  the reservoir water.