Comparative study on growth performance, phenotypic traits and genotypic variations of geo-graphically isolated two strains of koi (Anabas testudineus) exhibited in same environmental conditions.

Abstract

Local and Thai koi, samples collected from two different localities, were subjected to rear at the experimental ponds for a period of fifty days and the highest gain in length, weight and SGR were found in Thai koi as 12.23( + - )0.38, 55.83( + - )0.53 and 7.92( + - )0.11 respectively. Fourteen orphometric characters were studied where eleven showed (TL, SL, HL, HBD, LBD, PCFL, PELFL, AFL, UJL and LJL) significant difference in Thai koi than the local ones (P<0.01). Of the nine meristic characters no. of dorsal fin rays (hard), anal fin rays (hard), caudal fin rays and scale along Lt. line (lower) as recorded from the Thai koi were significantly higher (p<0.01) than the local koi. The no. of dorsal fin rays (soft) in Thai koi was also significantly higher (p<0.05) than local koi. The counted no. of vertebra were also unlike in local and Thai koi (25 incase of local koi and 26 incase of Thai koi). The genetic variation of local and Thai koi was studied through ten enzymes systems that provided eleven scorable loci. Seven out of 11 gene loci were monomorphic in both the populations, 4 were polymorphic in Thai and 2 displayed polymorphism in local population. The genetic distance between local and Thai population was (D = 0.134). Present study revealed that although both the local and Thai koi belongs to the same species, growth performance of Thai koi was faster compared to local koi within same condition. UPGMA tree formed 2 clusters which indicate that the genetic relationship among the two strains of koi collected from different geographic region. This is a preliminary study which gives insight to researcher to investigate the genotypic and phenotypic traits along with growth performances. A more comprehensive study is needed to address the short comings of culture aspects, stimulated genotypic and phenotypic variability of two different geographically isolated strains but cultured in same environment.