Problems With Neon Tetras

Neon tetras are hardy community fish when settled.
i Dwarf Gourami & Neon Tetras image by Ronnie from

Neon tetras are hardy fish once established, but they don't do well when faced with changes in water chemistry, temperature, stress and disease. All these conditions occur during and after the journey from the pet store, so neons are very delicate for the first week in their new home.

Water Chemistry

A cycled aquarium is essential when adding neon tetras. A tank with mature water is best, but if you're starting out, add a commercial beneficial bacteria solution to the water to kick-start the nitrogen cycle and buy a test kit to check for ammonia, nitrate and nitrite at least once a week. Neon tetras are sensitive to increased levels of ammonia and this chemical will kill your fish if left unchecked. The nitrogen cycle takes about four weeks to occur naturally; a cycling solution speeds up the process to about a week. Continue to check the water chemistry of a new aquarium for at least a month as a precaution.


A sudden change in water temperature causes stress and the bag of warm tank water from the pet store housing your neon tetras can cool down within 30 minutes. Pack the bag into a Styrofoam box to slow the process and once home, acclimate the fish by floating the bag, unopened, in your aquarium for at least 20 minutes to slowly raise the temperature and reduce temperature-induced shock.

Stress and Schooling

Neon tetras need other neon friends to feel safe, preferably a bunch of five or more. They are naturally schooling fish that show less stress when housed as a group and swim near the front of the aquarium out in the open. Solitary neons tend to hide and become an easy target for larger fish that bully loners in a tank.

Neon Tetra Disease

Fish are most susceptible to disease when their defenses are down from poor water quality or stress. Keep your aquarium water clean and well-maintained and your neon tetras stand a better chance of fighting off neon tetra disease. The condition is untreatable and extremely contagious, even to other types of fish. You won't know your new fish are infected until they display symptoms, by which time the rest of your tank may also be infected. Early signs are a white patch at the base of the dorsal fin which rapidly spreads to the rest of the body tissue. The only course of action is to remove and quarantine affected fish and once there are no more new cases, thoroughly clean your aquarium.

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