Bhatnagar Anita
The purpose of the present study was to investigate and compare the karyotypes of three Indian major carps, Catla catla (Hamilton, 1822), Labeo rohita (Hamilton, 1822), Cirrhinus mrigla (Hamilton, 1822) in terms of chromosomal architechture, karyotype formula and number of chromosomes from aquatic ecosystems of Haryana, India. Karyotypes of these carps were in-vestigated by examining metaphase chromosomes. The results indicated that the diploid (2n) chromosome number of all the three major carps was 50. Catla catla consisted of 22 acrocent-ric, 2 subtelocentric, 20 submetacentric and 6 metacentric chromosomes. Labeo rohita consis-ted of 32 acrocentric, 4 subtelocentric, 6 submetacentric, 8 metacentric while Cirrhinus mrigla consisted of 30 acrocentric, 8 subtelocentric, 6 submetacentric, 6 metacentric chromosomes. Centromeric Index, arm ratio and fundamental number was also determined. No heteromorphic sex chromosomes were cytologically detected. The variability in size, shape and arm number (NF) of chromosomes among these three species suggest that diversification in these fish spe-cies of same family is related to structural changes in chromosomes. Variations in karyotype formulae are also observed with respect to earlier studies which may be due to variations in ha-bitat conditions as a result of anthropogenic activities.
