Hexamita

Symptoms

Spotting illness early gives the best chance of a cure, so check your fish daily at feeding time. White, stringy, mucus-like droppings, loss of appetite, weight loss despite eating, darkening colour and listless behaviour. It often precedes Hole in the Head. If you see several of these signs together, act promptly rather than waiting.

Causes

An internal flagellate parasite that multiplies in the gut when fish are stressed by poor water, transport or overcrowding. It spreads through contaminated water and faeces. 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 metronidazole, ideally medicated in food while the fish still eats, alongside excellent water quality and raised temperature where the species tolerates it. 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 new fish, keep water clean and stable, and avoid the stress that lets this gut parasite take hold. 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.