Threadfin rainbowfish

Behaviour and habits

The threadfin rainbowfish is a delicate, elegant shoaler whose males trail long red-and-black threads from their fins, giving them a spectacular, almost feathery look. It is peaceful and a little shy, showing its best colours in a planted tank with soft, warm water and calm company. Kept in a group it becomes more confident, drifting among plants and displaying to its companions; with pushy tankmates it hides and fades.

What to feed, and how often

It has a small mouth and needs small foods — micro-pellets, daphnia and baby brineshrimp — fed one or two small meals a day. It is easily out-competed by faster fish, so make sure it actually gets food; a hungry threadfin quickly loses condition.

Water changes and maintenance

Change about 20–25% weekly in soft, warm water, matched gently to the tank. It dislikes hard water and sudden changes, and it does best in a stable, mature setup with plenty of plants.

Care and how easy it is

Not the hardiest rainbow; it wants soft, stable water and gentle tankmates in a planted tank, and is a poor choice for a hard-water community.

Common health problems

Sensitive to poor water; can suffer fin rot and starvation if out-competed.

If it gets sick

Make sure it gets food, keep the water soft and stable, and treat early if the fins look damaged or the fish goes thin.