Abnormal Buoyancy in a Convict Cichlid (Amatitlania Nigrofasciata) Associated With an Ovarian Carcinoma Invading the Swim Bladder

An 8-year-old female convict cichlid (Amatitlania nigrofasciata) was presented to the University of Wisconsin Veterinary Medical Teaching Hospital with a 2-month history of abnormal buoyancy; the fish spent most of its time in lateral recumbency on the aquarium substrate. During the initial visual examination of the patient in its transport aquarium, the fish was laterally recumbent on the bottom of the tank and had a mildly distended coelom. A transient response to empirical florfenicol therapy was reported, but the cichlid presented 1 month later in poor body condition and, again, in lateral recumbency. Owing to the poor prognosis, the fish was humanely euthanized and a necropsy was performed. The histopathologic results were consistent with a papillary carcinoma originating in the ovary, which invaded the caudal kidney and the swim bladder. The infiltration of the carcinoma into the swim bladder was suspected to be the primary cause of the clinically observed buoyancy abnormality.