Latin name: Other names: Pathogen: Symptoms:
Fish hang near the surface,
Fish show rapid breathing which manifests itself in rapid gill movements. They will swim at the surface gasping for air. Snails, and marsh snails (Melaniidae) get out of the gravel and move closer to the surface.
When fish stay for a long time in the water with low oxygen levels (lower than 3 mg/L), they start suffering from asphyxia and eventually die from suffocation. Oxygen deficit is caused by bad maintenance of the aquarium (rare water changes, gravel cleaning, dirty filter, etc) and overcrowding (more than 1 cm of fish length per 1L of water).
How to cure:
15% Hydrogen dioxide solution (1ml per 1L of water) will help temporarily.
Preventive measures include timely aquarium cleaning, water changes, aeration. Avoid overcrowding.