Trichodinid ciliates in two economically important fishes,Rastrelliger kanagurta(Perciformes: Scombridae) andOreochromis mossambicus(Perciformes: Cichlidae) from Kerala, India.

Abstract

Trichodinid ciliophoransare one of the main groups of fish parasitescausing damage to skin and gills,often leading to the death of the infested fish andare still a poorly studied group in India.A study was undertaken to assess the infestation and distributionof trichodinids from the skin and gills of two economically important fishesin India, RastrelligerkanagurtaCuvier, 1816and OreochromismossambicusPeters, 1852.Dried slides were prepared from the smears andimpregnated with silver nitrate (2%) and morphometriccharacteristics were madeusing photomicrographs produced from theslides.O. mossambicus was found positive for two species, viz., TrichodinamagnaVan As and Basson, 1989 and ParatrichodinaafricanaKazubski and El-Tantawy, 1986.R. kanagurta was found to be infested with Paratrichodina sp. Lom, 1963. Seasonal variations in the rate of parasite infestation were observed in T. magnaand P. africana from O. mossambicusand these parasites showed anincrease during post-monsoon while a decrease during monsoon. No seasonal variation was observed in Paratrichodinainfestation in R. kanagurta. The infection induced excessive mucus secretion, paleness in gills, and multifocal whitish areas and lesions that probably permitted entry of opportunistic bacteria. The present study reportsthe first record ofa Paratrichodina sp.onR. kanagurtaand T. magnaon O. mossambicus.