Treat repeated surface gasping as urgent
Increase surface agitation immediately and check whether the pump or filter stopped. Repeated mouth movements at the surface with fast gill movement are different from briefly searching for food.
Oxygen and gill problems
Warm water, heavy stocking and decomposing waste can reduce available oxygen. Ammonia, nitrite or gill parasites can also impair breathing even when an air stone is running.
What to do next
Test the water, stop adding food and remove decaying material. Use conditioned, temperature-matched partial water changes when appropriate. If several fish are affected, investigate the shared water urgently; if distress persists, contact an aquatic veterinarian.
When to get professional help
Seek urgent help for severe breathing difficulty, bleeding, raised scales or inability to stay upright. Record exact water results and recent changes. A separate hospital aquarium must also be adequately filtered and aerated; an uncycled bowl can make the problem worse.
Frequently asked question
Should I medicate before testing the water?
Check water and oxygen promptly. Treatment should follow the likely cause; avoid mixing remedies without qualified guidance.
Sources and further reading
General husbandry and health references. Individual fish and local conditions vary.