Infectious hematopoietic necrosis (IHN)

Rainbow trout fry experimentally exposed to infectious hematopoietic necrosis virus. Typical signs include darkening and exopthalmia (popeye) as shown by the fish in the lower portion of the photo. Other external signs may include fluid accumulation in the abdomen (ascites), trailing fecal casts, and small hemorrhages in the fins and body musculature.