Efficacy of sewage treated water on fish production
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Date
2021-09
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CCSHAU, Hisar
Abstract
During present investigation, growth parameters of Pangasius hypopthalamus, Cyprinus carpio haematopterus, Clarias batrachus and Catla catla were recorded in sewage treated water. The weight (18.16g), length (12.82 cm), weight gain (745.59 g), biomass (817.2 g), percent increment in weight (1021%) and percent increment in length (106.5%) was highest for P. hypopthalamus fishes cultured in sewage treated water with feed whereas these parameters significantly declined for fishes reared in sewage treated water without feed (165.09 g, 240.42 g, 254%, 74.9%). The survivability in sewage treated water without feed was 90 percent as compared to 100 percent in freshwater and sewage treated water with feed. The feed conversion ratio for fishes reared in sewage treated water with feed at 90th day was less (2.09) than that recorded in freshwater (2.41). The fishes cultured in sewage treated water with feed has higher specific growth rate (1.16%) and average daily weight gain (0.41 g/ day) as compared to fresh water (0.99%, 0.27 g/day) and sewage treated water without feed (0.61%, 0.10 g/day). The growth of P. hypophthalmus showed significant positive correlation with temperature, conductivity, total soluble solids, dissolved oxygen and hardness and salinity of sewage treated water, however, ammonia, nitrite and alkalinity had no correlation. Sewage treated water showed significantly lower weight and length of C. carpio haematopterus and C. catla as compared to freshwater. Maximum weight and length of C. batrahus was recorded at 60th day (11.08g, 11.22 cm) as compared to 30th day (6.46g, 8.71cm) and 0th day (1.86g, 6.21cm). Significant positive correlation between weight, length of C. batrachus and temperature (0.93, 0.91), conductivity (0.98, 0.94), total dissolved solids (0.92, 0.94), salinity (1.00, 0.98), dissolved oxygen (0.87, 0.81) and ammonia (0.87, 0.89) was recorded. A significant negative correlation was recorded with pH (0.87, 0.85) and alkalinity (0.93, 0.90) whereas nitrite content did not show any correlation with C. batrachus growth parameters. The net accumulation of heavy metal in fish tissues was in the order: Fe>Mn> Cu > Zn. The bioaccumulation trend among the five fish organs were: Gills > Muscle > Brain > Heart > Stomach. Nickel and chromium were not found in sewage treated water. The sewage treated and biofiltered Azolla water were statistically comparable with each other in terms of change in P. hypopthalamus weight and length. There was significant decrease in the conductivity, total dissolved solids, salinity, ammonia, hardness and alkalinity of sewage treated water due to Azolla culture after 21 days as compared to 0 day. Azolla culture significantly reduced the heavy metal concentration (0.035 mg/l) in sewage treated water after 21 days from 0.107 mg/l at 0 day. Among the heavy metals, iron concentration was significantly higher (0.140 mg/l) than zinc (0.113 mg/l), copper (0.027 mg/l) and manganese (0.005 mg/l) although all were well below the permissible limits.