Ichthyophthirius multifilis (Protozoa) in Gasteropelecus sternicola (Linnaeus, 1758) collected in the area of Belém, State of Pará, Brazil

The present study describes for the first time Ichthyophthirius multifilis infecting twenty ornamental fishes Gasteropelecus sternicola (white butterfly fish). Parasites were found in 100% of examined fishes. Light microscopy and scanning electron microscopy (SEM) were used in this exam. SEM showed fins destroyed by the parasites action. High prevalence of the parasitism has a high concern as those fishes are of commercial importance for Brazil.