Additional novel Cryptosporidium genotypes in ornamental fishes

Current knowledge on the prevalence and genotypes of Cryptosporidium in fishes is still limited. This study investigated the prevalence of Cryptosporidium species in 171 ornamental fishes, belonging to 33 species, collected from 8 commercial aquariums around Perth, Western Australia. All samples were screened by nested PCR targeting the 18S rRNA locus. A total of 6 positives were identified by PCR at the 18S locus from 4 different species of fishes (red eye tetra, Moenkhausia sanctaefilomenae; gold gourami, Trichogaster trichopterus; neon tetra, Paracheirodon innesi; goldfish, Carassius auratus auratus), giving an overall prevalence of 3.5% (6/171). Four different genotypes were identified, only one of which has been previously reported in fish; piscine genotype 4 in a neon tetra isolate, a rat genotype III-like isolate in a goldfish, a novel genotype in three isolates from red eye (piscine genotype 7) which exhibited a 3.5% genetic distance from piscine genotype 1 and a piscine genotype 6-like from a gold gourami (1% genetic distance). Further biological and genetic characterisation is required to determine the relationship of these genotypes to established species and strains of Cryptosporidium.