Somatic chromosomes of two Indian estuarine Catfishes,Plotosus canius(Plotosidae) andPseudeutropius atherinoides(Schilbeidae), were studied from kidney cells of both sexes. The diploid complement ofP. caniusincludes 36 chromosomes of which there are 5 pairs of metacentric, 5 pairs of submetacentric and 8 pairs of acrocentric nature (FN = 56). In the 2n= 58 karyotype ofP. atherinoides, there are 14 pairs of metacentric, 6 pairs of submetacentric, 1 pair of subtelocentric and 8 pairs of acrocentric chromosomes (FN = 98). No sex chromosomes were observed in either species. The results show that the family Plotosidae may be an exceptional group of Siluriformes characterised by low diploid numbers. The Schilbeidae, on the other hand, is evidently less divergent.