Camallanus Worms

Symptoms

Spotting illness early gives the best chance of a cure, so check your fish daily at feeding time. Red or brown thread-like worms protruding from the fish's vent (anus), plus bloating, wasting and loss of appetite in heavy cases. If you see several of these signs together, act promptly rather than waiting.

Causes

Internal parasitic nematodes introduced with new fish (especially livebearers) that live in the gut and emerge from the rear of the fish. In nearly every case the underlying trigger is stress, poor water quality, or the introduction of an infected fish - all of which weaken a fish's natural defences.

Treatment

Treat with a dewormer containing levamisole or fenbendazole, repeating after 1-3 weeks to catch the life cycle, with gravel vacuuming between doses to remove expelled worms and larvae. Treat the whole tank.

While treating, increase aeration, remove activated carbon from the filter (it absorbs medication), finish the full course even after the fish looks better, and keep the water immaculate with regular changes. Always dose for the tank's true water volume and follow the product instructions.

Prevention

Quarantine and deworm new fish (especially livebearers) before adding them to your main tank. The golden rules are simple: quarantine every new fish for 2-4 weeks, never overstock or overfeed, avoid sudden temperature or chemistry swings, and do regular partial water changes. A stable, clean, low-stress aquarium prevents the large majority of disease.

FAQ

This information is general guidance, not veterinary advice. Consult an aquatic vet for serious cases.