Karyotypes of 7 species of Thai freshwater fish were studied by using the method of cell culture of the caudal trunk tissue and staining the chromosome with Giemsa. The metaphase spreads obtained by this method were in good quality with dispersed chromosomes. The diploid numbers and the morphology of chromosomes of these 7 specifics were as follows: 1. Blotch snakehead fish (Ophicephaius lucius) 2n=88, comprising of 1 metacentrci pair and 43 acrocentric pairs. 2. Rohu (Labeo rohita) 2n=50, comprising of 15 metacentric/submetacentric and 10 acrocentric pairs. 3. Common carp (Cyprinus carpio) 2n=100, comprising of small and different types of chromosomes which were not classified definitely. 4. Common climbing perch (Anabas testudineus) 2n=46, comprising of 4 submetacentric pairs and 19 acrocentric pairs. 5. Snakeskin gourami (Trichogaster pectoralis) 2n=46, all being acrocentric chromosomes. 6.Common silver barb (Puntius Gonionotus) 2n=50, comprising of 15 metacentric/submetacentric pairs and 10 acrocentricpairs. 7. Freshwater catfish (Clarias macrocephalus) 2n=54, comprising of 18 metacentric/submetacentric pairs and 9 acrocentric pairs.