Aquarium tropical fish and fish diseases


Lack of dissolved oxygen

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Lack of dissolved oxygen

Latin name:
Other names:
Symptoms: Dead fish stay with open mouth, Fish breathair from the surface of the water (swalling air), Fish hang near the surface, Brightening (lighting) of body colors, Protruding operculi (gill covers)

Fish will swim at the surface gasping for air. Spread gill covers the condition that remains even after optimal conditions have been provided. Fish will show skin discoloration. The condition is associated high mortality rates in the aquarium. The mouth will remain open after fishs death.

Lack of dissolved oxygen in the water causes < ahref="/cgi-bin/pub/diag?c=v&id=15">asphyxia, or suffocation. Asphyxia Is caused by overcrowding, decaying bits of uneaten food, insufficient amount of plants in the aquarium with dim lighting, excessive amount of plants (at nighttime), a small volume of the container without artificial aeration during transportation.

How to cure:
Artificial air aeration of water. Remove food remnants from the gravel. Replace two-thirds of water with fresh settled water. To rule out some infectious diseases (accompanied by symptoms typical of asphyxia) such as Costia and Dactylogyridea, put fish into fresh, oxygen-rich water. If asphyxia is caused by an infectious disease, fishs condition will not improve.


It is vital that you determine the safe holding capacity of the fish tank. For example, a 5-cm fish needs 2 liters of space. A fish, between 5 and 11 cm in length, requires 4 liters. A fish more than 11 cm in length needs 10 liters. There should not be too many plants in the tank they must not take up more than two-thirds of the aquarium. Food should be eaten within 5-10 minutes. Live foods are preferable.

Fish susceptible to the disease/disorder: