Hydro biological Characteristics of Some Semi-intensive fish culture ponds of Lumding town of Nagaon district, Assam

Hydrobiological assessment is useful for assessing the ecological quality of aquatic ecosystem since biological communities integrate the environmental effects of water chemistry. Ten fish ponds from Lumding town, which were under semi-intensive culture practice, were selected for hydrobiological investigations. Physico-chemical properties were studied for a period of two years from July 2009 to June 2011.Some selected parameters like pH, dissolve oxygen, free carbon dioxide, TDS , total alkalinity, total hardness, sp. Conductivity, transparency and BOD were studied on some fish pond water. P H ranges from 6.1 to8.5. Temperature ranges from 18 0 C-32 0 C. Color shows light green to dirty green. Transparency ranges 17-42cm, dissolve oxygen ranges from 3.2-8.0 ppm, total alkalinity ranges from 7.9-20.0ppm, Hardness ranges from 60-135 ppm, sp.conductance ranges from123-247μmhos/cm and BOD ranges from3.1-5.0ppm. The phytoplankton belonging to division Chlorophycae and Cyanophycae are predominant over the others and zooplanktons belonging to group Protozoa, Rotifers are predominant. . A total of 30 species of belonging to Chlorophycae. Cyanophycae were identified and a total of 20 species of Rotifera, 2 species of Cladocera and 1 genus of Copepods were found. The present study is expected to help achieve better and higher yield of fish by the fish farmer with increasing awareness regarding the hydrobiological feature of the pond and implement scientific management practices accordingly