Comparison of growth performance and morphological variation among three carp species (Cyprinus carpio, Hypophthalmichthys molitrix, and Labeo rohita)

This study was designed to analyse the water quality parameters and external morphological characters of three selected carp fish species i.e., Cyprinus carpio, Labeo rohita, and Hypothalamus molitrix from the Hub Dam of District Lasbela, Baluchistan. About Sixty specimens were collected for each carp fish species from April 2019 to March 2020, and their morphological characters were measured. The overall study of water quality parameters of Hub dam was found in the optimal range. The results of the Cube law revealed that the regression coefficient b-value was<3.0, which means that these species show positive allometric growth patterns that are, b = 2.07 for C. carpio, b = 2.04 for H. molitrix, and b = 0.12 for L. rohita. Moreover, the Correlation value ‘r’ between length and weight data for C. carpio and H. molitrix was found moderate and significant (r > 0.60; p < 0.05), while weak (r < 0.50; p < 0.05) and insignificant in L. rohita, respectively. The mean values of condition (K) and relative condition factors (Kn) were 1.0 which shows a good condition in Hub dam for fish growth. The overall results of linear relationships between 18 morphometric characters vs whole body growth (TL) revealed that a strong correlation (r > 0.70) was observed among TL vs FL and TL vs LD and moderate (r > 0.60; p < 0.05) and negative correlation also seen in between TL vs BDL and in most meristic characters of C. carpio. Likewise, mostly moderate (r > 0.60) and weak (r < 0.50) types of correlation were seen in most morphometric and meristic characters of H. molitrix and L. rohita, except few meristic characters of L. rohita show negative type relation with body growth (TL). This study was the first approach to examine the growth patterns of different carp species of Hub dam and observe their morphological variations among these carp species that have great potential value in systematics and fisheries management.