First occurrence of Metanophrys sinensis Song & Wilbert, 2000 (Protozoa: Ciliophora: Scuticociliatida) outbreak in a marine ornamental fish: Morphological and phylogenetic analysis

Abstract

A scuticociliatosis outbreak with high mortality was recorded in the clownfish breeding facility of the ICAR-NBFGR, Maharashtra, India. Moribund fish juveniles showed abnormal swimming and high mucus secretion with energy loss. Microscopic investigation found that all moribund juveniles had dense parasites on their gills, fins, and almost the whole-body surface. Thin to elongated oval-shaped ciliates Metanophrys sp. with pointy anterior end (25-50 × 10-20 µm) were detected and collected for further observation. The causative parasite was characterised by 18 SSU rRNA gene sequencing method using universal and specific primers. The causative ciliate was confirmed as Metanophrys sinensis Song & Wilbert, 2000, based on 97 % gene similarity in BLAST analysis results. The accession codes OM055651.1 (universal primer) and ON329185.1 (specific primer) were acquired after gene sequences were uploaded to GenBank. On the basis of available literature, this is the first occurrence record of scuticociliatosis outbreak caused by Metanophrys sinensis in the marine ornamental fish hatchery in India and elsewhere.