Epicellular coccidiosis in goldfish

Abstract

In a goldfish stock held in a pet fish pond, heavy coccidian infection, caused by an epicellularly developing Goussia species, appeared in April of 3 consecutive years (2014 to 2016). The shape and size of the oocysts resembled those of an inadequately described species, Goussia carassiusaurati (Romero-Rodriguez, 1978). In histological sections, gamogonic and sporogonic stages infested mostly the second fifth of the intestine, where almost all epithelial cells were in - fected. Both gamonts and young oocysts occurred intracellularly but in an extracytoplasmal position, seemingly outside the cells. Oocysts were shed non-sporulated. Spheroid to ellipsoidal nonsporulated oocysts measured 12.4 × 13.5 μm on average, but after 48 h sporulation in tap water they reached a size of 16 × 13 μm. The 4 elliptical sporocysts located loosely within the sporulated oocysts measured 13 × 5.4 μm. The oocysts and sporocysts were smaller than those of the betterknown Goussia species G. aurati (Hoffman, 1965).