Ichthyophthirius schlotfeldti Yunchis, 1997 (Ophryoglenidae) was described by the junior author from aquarium fishes from South-East Asia. In the present paper this species is separated into a new genus Neoichthyophthirius gen. n. The reproduction of this species takes place within the epithelium of fishes and not in water as in Ichthyophthirius multifilius. Neoichthyophthirius schlotfeldti has a ring-shaped macronucleus with ends overlapping. Maximum temperature, when the reproduction is possible, is about +34 degrees. The parasite is pathogenous and causes a mortality of aquarium fishes.