Growth performance of metals mixture stressed fish in earthen ponds

The present research was undertaken to elucidate the effects of sub-lethal concentrations of metals (zn+pb+mn) mixture on the growth performance of hypophthalmichthys molitrix,ctenopharyngodon idella,cirrhina mrigala,labeo rohita and catla catla. fish were given sublethal stress under controlled laboratory conditions,separately,for a period of 90 days and then they were transferred to the semi-intensive ponds. the growth of five metals mixture stressed fish species was monitored for a period of 14 fortnights in earthen ponds and compared with the control group. data were collected on fortnightly basis to check the growth performance of each fish species in terms of average wet weight,fork and total length increments,specific growth rates and feed conversion ratios under the composite culture system. highly significant differences at p<0.01 were observed for average wet weight (g),fork and total length (mm) increments in metals mixture stressed fish as compared to control group and also among five fish species. the control fish showed significantly better specific growth rate than that of metals mixture stressed fish. due to varying growth potential,species specific variations were found among all fish species for specific growth rates. among all the mixture stressed fish species reared in earthen ponds,maximum increase in average wet weight and also specific growth rate were shown by cirrhina mrigala,whereas,ctenopharyngodon idella exhibited maximum average fork and total length increments,respectively. however,statistically higher average wet weight increment and specific growth rate were found as 611.75±1.52 g and 291.31±2.26 for labeo rohita reared in control pond. among all the five control fish species,the maximum average fork and total length increments were shown by cirrhina mrigala. highly significant differences were recorded for feed conversion ratios of stressed and control fish ponds. the feed conversion ratio of metals mixture stressed fish pond was lower (1:7.94) in comparison to the control fish pond,for which it was computed as 1:8.44. feed conversion ratios of ponds varied significantly among various fortnights of the study period.