Neon tetras (Paracheirodon innesi) are from the Amazon River. They belong to the family Characidae, most commonly referred to as the Characins. They look very similar to cardinal tetras (Paracheirodon axelrodi) except that in neon tetras only the lower back half of their body is red in color. In cardinal tetras the red portion extends from the head to the tail on the lower half of their body. The care of both cardinal and neon tetras is identical.
Neon tetras are peaceful fish that do well in a community aquarium as long as the other fish are not large enough to eat them. Neon tetras only grow to about 1.5 inches long (3.8 cm) and their slender bodies make it easy for large fish to eat them. I've seen large angelfish swallow neon tetras whole. Keep this in mind when choosing tankmates for your neon tetras.
Like all fish from the Amazon, neon tetras do best in soft, slightly acidic water. The water temperature should be between 70-79°F (21-26°C). They swim in the middle to lower layers of the aquarium. They are shoaling fish and so you need to keep several (at least 4) neon tetras together in your tank. They won't thrive as solitary fish.
They are omnivores (both plant and meaty foods) and will readily eat flakes, frozen, freeze-dried, and live foods.
Spawning and Fry
They are egglaying fish and will sometimes spawn in the aquarium. Sexing them is rather difficult because males and females are identical in color. Sometimes females will have a more rounded body shape than the males if the female is full of eggs. As with all fish, feeding them live foods such as brine shrimp or other meaty type foods (tubifex worms, blood worms) seems to get them into breeding condition.
It is best to place the pair (or several neons if you don't know what sex they are) in a separate breeding tank with some plants (floating is best) and soft, slightly acidic water (pH around 6.0-6.2). They won't breed in alkaline, hard water. You can filter the water through peat or add a thin layer of peat to the substrate. Make sure there are no other additives in the peat that could be harmful to the fish. There should be no lighting in the tank, becaue they won't breed unless the lighting is very dim.
During spawning neon tetras scatter their eggs. After spawning is complete remove the adult fish so they don't eat the eggs. The eggs hatch in about 24 hours and once they are free swimming neon tetra fry can be fed commercial liquid fry food or infusoria. Later, when they are bigger, the frys' diet should be supplemented with newly hatched brine shrimp and powdered fry food.