Cutaneous angiomatosis-like in koi carp (Cyprinus carpio koi): Clinical-pathological investigations

The skin represents an indicator of an animal's health status. Causes of cutaneous diseases in fish most often trace back to biological agents. However, fish skin diseases can also arise from a complex interaction of infectious and non-infectious causes, making it more difficult to identify a specific aetiology. In the period between April and September of the years 2019-2022, four koi carp (Cyprinus carpio koi) from two European countries presented with multifocal, irregularly round, few mm to 1 cm, variably raised cutaneous reddened areas. The fish displayed good general condition. Cutaneous samples, investigated by microbiological and molecular methods and microscopy, did not indicate a primary pathogenic agent. Gross and histological findings of the cutaneous biopsies were consistent with a multifocal/reactive process centred on dermal vessels. The histological features were reminiscent of angiomatosis, a benign proliferative condition affecting the dermal vessels of mammals, including human patients. The clinical-pathological presentation and the dermatologic condition that affected the koi carp are discussed and compared with the veterinary and human literature.

Automated summary

The skin is an indicator of an animal's health status, and cutaneous diseases in fish are often caused by biological agents. However, fish skin diseases can also result from a complex interaction of infectious and non-infectious causes, making it difficult to identify a specific cause. Four koi carp from two European countries exhibited multifocal, irregularly round, raised cutaneous reddened areas between April and September 2019-2022. Microbiological and molecular analysis did not reveal a primary pathogenic agent, but histological findings indicated a reactive process centered on dermal vessels. The condition resembled angiomatosis, a benign proliferative disease affecting the dermal vessels of mammals.