William H Wildgoose MRCVS
Pet fish vet
Internal tumours in goldfish
Unlike koi, goldfish rarely develop tumours inside the body cavity and those that do tend to be smooth and localised tumours. These are often difficult to identify in the early stages since they rarely cause clinical problems and are usually found by accident. As the tumours increase in size, they may cause asymmetric bulging or swelling of the belly, and sooner or later affect the fish’s health causing it to lose weight or develop secondary problems. Many are spindle cell tumours although histological identification can be difficult. Surgical removal may be possible in some cases although it is high risk, with many potential complications.
This fish developed abdominal swelling over one month and had mild ‘dropsy’ (skin oedema). A large bulbous tumour occupied much of the left side and represented 20% of its body weight. It was confirmed as a spindle cell tumour by a pathologist and kidney disease probably caused ‘dropsy’.
The rear chamber of the swim bladder appears closer to the spine and front chamber. The area occupied by the tumour, towards the rear of the body cavity has a uniform radiographic appearance with lack of detail, whereas the area below shows some dark irregularity due to gas in the bowel.
This large firm mass could be easily felt when examined under anaesthetic. Externally, there was some local skin ulceration where it bulged noticeably on the left side. Internally, it was firmly adhered to the body wall. Identification of the tumour type was unclear but it was similar to lymphosarcoma.
This fish developed abdominal swelling over one month and had mild ‘dropsy’ (skin oedema). A large bulbous tumour occupied much of the left side and represented 20% of its body weight. It was confirmed as a spindle cell tumour by a pathologist and kidney disease probably caused ‘dropsy’.