Comparative karyotype analysis of some indigenous and exotic cichlids of south india

Cichlids are one of the most species rich fish families in the world. Researchers worldwide are attracted to cichlids due to their vast diversity. Fish cytogenetics plays an important role in classification and understanding evolution. The chromosome number and morphology of two indigenous Cichlids- Etroplus suratensis and Etroplus maculatus, and an exotic cichlid, Pterohyllum scalare are determined and compared in the present study. The method of Barreto Netto et al. and Nagpure et al. was followed for preparing chromosome spreads, which were photographed and measured. The chromosome compliment of E. suratensis consisted of 2n= 48 subtelo/acrocentric chromosomes. The chromosome compliment of E. maculatus consisted of 2n= 46 with a pair of metacentric chromosomes, which can be considered as marker chromosomes, and twenty two pairs of subtelo/acrocentric chromosomes. The chromosome compliment of Pterohyllum scalare consisted of 2n= 48 with 3 pairs of metacentric and 21 pairs of subtelo/acrocentric chromosomes. E suratensis retains the primitive ancestral karyotype and E. maculatus shows a derived, advanced karyotype. Derived karyotype occurs from ancestral karyotypes as a result of chromosomal rearrangements- fusions and inversions.