Author(s): SAXENA M
The length-weight relationship of carps was studied in Raipur reservoir, Gwalior from April, 2009 to March, 2011. Four major carps species, viz., Catla catla, Labeo rohita, Cirrhinus mrigala and Cyprinus carpio were cultivated in the reservoir. The growth of carps was studied from April, 2009 to March, 2010 during first year, while in second year growth studies were conducted during August, 2010 to March, 2011. In the year 2010-11, however, the reservoir dried up during the period from April, 2010 to July, 2010 due to low rains during the rainy season and high evaporation during the summer. The values of ‘n’ for C. catla, L. rohita, C. mrigala and C. carpio were 2.438, 3.399, 2.844 and 2.358 respectively in this water body during 2009-10, while the values of ‘n’ for C. catla, L. rohita, C. mrigala and C. carpio are 2.856, 2.827, 2.771 and 2.394 respectively were during 2010-11. The value of coefficient of correlation (r) between length and weight shared a perfect positive relationship in all the fishes studied during both the years of study. A total of 200 specimens of each of four species were taken and a logarithmic graph plotted between length and weight has shown a straight line in all the four carps. The condition factor ‘K’ for C. catla revealed that with the progression of growth of the fish, the well being of fish decreased as this factor is showing a decreasing pattern while in L. rohita fish attains good growth and size in comparison to other fishes and a positive pattern of condition of fish was observed. The condition factor ‘K’ for C. mrigala revealed that with the progression of growth of the fish, the well being of fish increased with increased age and in C. carpio a decreasing pattern with the progression of growth in the fish was shown, thus the well being of fish was also low. The absolute growth may be concluded that the growth increment during first year of culture the growth was highest in L. rohita in comparision to other carps while in second year maximum growth was exhibited by C. catla and minimum growth by C. carpio. It was found that rohu had good absolute growth in the reservoir in the first year. However, in second year of study, it was catla who had a little edge over rohu. C. carpio grew the least in comparison to other carps. On the basis of physico-chemical characteristics of the Raipur reservoir, it may be classified as mesoeutrophic one.