Experimental infections of a ciliate Tetrahymena pyriformis on ornamental fishes

Abstract

Experimental infection of Tetrahymena pyriformis was conducted on ornamental fishes with skin wounded by acetic acid treatment. Among fishes used in this experimental infection, guppy Poecilia reticulata, pristella Pristella maxillaris, neontetra Paracheirodon innesi and cherry barbs Puntius titteya proved to be sensitive to challenge, while medaka Oryzias latipes, dwarf gourami Colisa lalia, goldfish Carassius auratus, platy Xiphophorus maculatus and angelfish Pterophyllum scalare were resistant. In catfish Corydoras aeneus infection was unsuccessful. Exposure to Tetrahymena at ≥100 cells/mL at 25 to 30°C and at pH of 6.0 to 8.0 resulted in the successful infection of some sensitive fish species. Histological and bacteriological observations suggest that deeply destroyed skin tissues from the acid-treated method are the primary factors in successful infection.