Karyotype Analysis of the Hybrid, Thai Red Tilapia (Oreochromis niloticus Linn. X Oreochromis mossambicus Linn.)

Abstract

Thai Red Tilapia is the hybrid fish between Oreochromis niloticus Linn. and O. mossambicus Linn. The chromosomal constitution of this hybrid were investigated using high quality metaphase preparations obtained from their bone marrow. The diploid chromosome of Tilapias consisted of 22 chromosome pairs (2n = 44). However, the morphology of their chromosome types were different. The karyotype of O. niloticus consisted of 18 subtelocentric (st), 26 acrocentric (a) whereas 6 submetacentric (sm), 10 st, 28 a and 2 sm 6 st, 36 a were observed in O. mossambicus and Thai Red Tilapia respectively. The arm number of O. niloticus, O. mossambicus and Thai Red Tilapia were 62, 60 and 52 respectively. The heterochromatic of the short arms of all Tilapias were also observed. The karyotypic differences between O. niloticus, O. mossambicus and the hybrid, Thai Red Tilapia will be useful for strain classification and the improvement of commercial Tilapias production.