N.C. Ujjania et al / Research Journal of Biology (2012), Vol. 02, Issue 01, pp. 50-56 ISSN 2049-1727 Available online at www.scientific-journals.co.uk 50 Research Paper Length-Weight Relationship and Condition Factors of Indian Major Carps (C. catla, L. rohita and C. mrigala) in Mahi Bajaj Sagar, India N.C. Ujjania 1* , M.P.S. Kohli 2 and L.L.Sharma 3 1 Department of Aquatic Biology, Veer Narmad South Gujarat University, Surat, Gujarat – 395007 (INDIA) 2 Central Institute of Fisheries Education, Deemed University (ICAR), Off Yarri Road, Versova, Andheri (W), Mumbai – 61 3 Department of Aquaculture, College of Fisheries, MPUAT, Udaipur (Rajasthan) * E-Mail: ncujjania@yahoo.com Abstract In this paper, length-weight relationships (LWR), condition factor (K) and relative condition factor (Kn) for three commercially important Indian major carps (Catla catla, Labeo rohita and Cirrhinus mrigala) from Mahi Bajaj Sagar are described. Mahi Bajaj Sagar-a freshwater reservoir, is situated in Banswara district of Rajasthan. This large sheet of water is an important major water body of the west coast river system of India. LWRs parameters are calculated for the three carp species and found significant. The correlation coefficient ‘r’ was significant and observed to be 0.918, 0.976 and 0.970 in catla, rohu and mrigal, respectively for pooled data. However, these values ranged from 0.664-0.903, 0.741-880 and 0.819-0.967 for catla, rohu and mrigala, respectively in different length groups. In LWR (W=aL b ) values of exponent ‘b’ were observed to be 3.275 for catla, 3.376 for rohu and 3.362 for mrigal from pooled data whereas such values varied from 3.160-3.805 for catla, 3.110-4.574 for rohu and 2.498-3.375 for mrigala in different length groups. The values of ‘K’ were 3.083 in catla, 1.695 in rohu and 1.714 in mrigal from pooled data. Moreover, it is fluctuated between 2.788-3.094 in catla, 2.011-2.213 in rohu and 1.523-1.962 in mrigal for different length groups. The values of relative condition factor (Kn) were observed in range 1.000-0.999 in different length groups and 1.018-0.998 for the pooled data of selected species. These parameters have been found very useful to evaluate the wellbeing of populations, their biology for scientific management of fisheries and stock assessment. Keywords: Length-Weight Relationships, Indian Major Carps, catla, rohu, mrigal, Isometric, Allometric Growths 1. Introduction Computing mathematical relationship between length (total length, standard length) and weight of fish is an important aspect of applied fishery biology. Length-weight relationships provide basic information in fisheries biology and therefore, useful to determine the weight of an individual fish of known length or total weight from length-frequency distribution (Forese, 1998 & Koutrakis et al, 2003). This relationship was initially used to obtain information on the growth condition of fish and to find out whether the somatic growth was isometric or allometric (LeCren, 1951 & Ricker, 1975). Further, the condition factor (K) and relative condition factor (Kn) are the important biological parameters which indicate the suitability of a specific water body for growth of fish (LeCren, 1951). The condition factor is an index of species average size while relative condition factor is the ratio between observed weight and calculated weight of the fish. The values of these factors depend on physiological features of fish namely maturity, spawning, environmental factors and food availability in a water body. Length and weight of Indian major carps in relation to