Hiding abnormally
Fish hides behind rocks or suchlike, appearing seldom if ever.
Loss of scales
Scales are missing on skin, usually in several places.
Bare rays
All interstitial tissue on fins has been eaten away.
Fish is fading away, looks as if it is starving to death.
Exophthalmia - bilateral
Both eyeballs of fish are protruding.
Exopthalmia - unilateral
One eyeball of the fish is protruding.
Faded colours
Colours of fish look washed out compared to normal.
Growth poor
Parasite infested fish show very slow or no growth, as parasite is taking the food.
Loss of balance
Fish keeps falling from its attempted swimming pattern.
Muscular atrophy
Muscles of fish show evident wasting away.
Ulcers - irregular
Irregular shaped ulcers are evident on the skin.
Abdomen sunken
The lower part of the fish's body is hollow and wasted.
Listless and lethargic
Fish moves very lazily in water, much less than normal, lacks interest.


Bacterial infection by Nocardia spp. Mostly identified as Nocardia seriolae. 


Virulent disease, difficult to treat succesfully. Strict hygiene is essential for prevention and cure of this disease.


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DNA and RNA diagnostic references

Detection of fish nocardiosis by loop-mediated isothermal amplification.

From  DOI: 10.1111/j.1365-2672.2006.02872.x

T.Itano et al. 


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