Strawberry Disease in Rainbow Trout– Histopathology

Figure 1. Strawberry disease in rainbow trout in freshwater showing loss of scales, and accompanying haemorrhage into the scale pockets. Note the severity of the dermal inflammation, which is mostly mononuclear, and largely avoids the epidermis.

Strawberry Disease (SD) is a chronic, nonlethal skin condition that affects Rainbow Trout (Oncorhynchus mykiss) in the United States, several European countries (Scotland, England, Switzerland, Germany, France, among others), Chile and Peru (Sandoval 2017, unpublished report). In Europe it is also known as Red Mark Syndrome (RMS) or Cold-Water Strawberry Disease (CWSD). SD is characterized by raised, sometimes bright red inflammatory lesions that can occur in almost any size of fish bigger than fingerlings, but usually in growing or market-sized fish. The disease presents as...