Oxygen deficiency

Symptoms

Listless and lethargic
Fish moves very lazily in water, much less than normal, lacks interest.

Haemorrhages fin base only

Bloody inflammation of mouth
Mouth area shows very bloody lesions and bleeding.

Diminished Flight Reflex
Fish is unresponsive to human or other approaches

Stops feeding
Fish often stop feeding entirely

Haemorrhages of the gills

Breathing at surface
Fish stays at surface usually at an inclined angle and breathes or sucks air.

Dissolved oxygen low < 6mg\L
Most aquatic fish in freshwater or seawater require oxygen levels above 6mg/L. Check oxygen level.

Gills pale
Instead of a normal bright red colour the gills are very pale in colour.

Haemorrhagic Eyes
Eyes are shot with bloody lines.

Hanging at surface
Fish stays at water surface all the time.

Hypoxia low oxygen levels

Respiration rapid
Fish is breathing very fast, much faster than is normal.

Insufficient oxygen. Can be caused by a rise in temperature, Pond or tank too crowded and insufficient aeration level.

Without fast correction, many or most fish will die. Fish farmers should have automatic warning systems installed, to prevent losses.

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