Vitamin B2 deficiency (Riboflavin Deficiency)


Abnormal pigment of iris
The irises of the fish's eyes are abnormally coloured.
Cloudy lens of Eyes.
Lens of eyes appears opaque as if a film has been placed on them.
Corneal opacity
Cornea of eye becomes totally opaque.
Dark body colouration
The colours of the fish are darkened beyond their normal shade.
Haemorrhages - skin
Bloody haemorrhages are apparent over several parts of the skin.
Growth poor
Parasite infested fish show very slow or no growth, as parasite is taking the food.
Haemorrhagic Eyes
Eyes are shot with bloody lines.
Fish shows a real aversion to any light, swims away immediately from any light diected towards it.
Haemorrhages - fins
Fins are bleeding.
Eye cataracts
Listless and lethargic
Fish moves very lazily in water, much less than normal, lacks interest.
Loss of membrane & rays
Fins are eaten away, both the rays & the interstitial membranes between
Lateral curvature of the spine.
Spasms - convulsions
Fish appears to be having a fit, jerking and twisting abnormally.


Lack of riboflavin in diet.

Validation: Low activity of erythrocyte glutathione reductase, low Liver or Kidney levels of Riboflavin.


Good if caught early. If not noticed many losses can occur, as even later correction will not repair the damage.

Cloudy lens is not reversible, but fish may survive; market value of fish is greatly reduced however. Haemorrhaging may stop with the addition of Riboflavin to the diet.


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Ensure that adequate Riboflavin is included in the diet, at all stages.


Dr. Hughes, Stephen
National Biological Service
Maryland Cooperative Research Unit


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