Possible signs of disease in fish:

  • Distended abdomen
  • Darkened skin colour
  • Petechial (pinpoint) haemorrhages at base of fins
  • Haemorrhaging of the gills
  • Swollen organs (kidney and spleen)
  • Possible long, white discharge from anus
  • Bleeding at base of fins
  • White faecal casts
  • Swollen stomach region (ascites, caused from accumulated fluid)
  • Exophthalmus (pop eye)
  • Pale gills
  • Bleeding eyes and fin rot are also common
  • Ecchymotic (bruise-like) skin haemorrhages may be present

Body condition index:

The condition index of fish can be determined by dividing its actual weight by its expected weight, and then multiplying this by 100%. A fish of normal weight should have a body condition index of 100 percent, so if its percentage was 80, for example, this fish would be seen as under the normal weight range for that specific species.