Threadfin rainbowfish tank mates
A 3.5 cm rainbowfish with spectacular trailing fin extensions on males. Peaceful and very slow-moving. Extremely vulnerable to active tank mates that shred the threadfins.
Lists below are built from this species record (safest, best with, risky, unsafe) — each link opens a pair-level check, not a guarantee.
Best tank mates (on file)
Merged from conservative safest and best with fields — de-duplicated by species.
The Threadfin rainbowfish profile lists Chili Rasbora as both safe and a recommended pairing. Chili Rasbora schools in groups of 8 or more, so plan room for the whole group rather than one fish.
The Threadfin rainbowfish profile lists Corydoras Catfish as both safe and a recommended pairing. Corydoras Catfish schools in groups of 6 or more, so plan room for the whole group rather than one fish. Corydoras Catfish swims in the bottom zone while Threadfin rainbowfish stays in the top, so the two will not crowd the same water column.
The Threadfin rainbowfish profile lists Dwarf Gourami as a recommended pairing. Dwarf Gourami grows bigger than Threadfin rainbowfish (8cm vs 3.5cm). Stock the Threadfin rainbowfish group large enough to outnumber the Dwarf Gourami, or the smaller fish ends up bullied or off food.
The Threadfin rainbowfish profile lists Ember Tetra as both safe and a recommended pairing. Ember Tetra schools in groups of 8 or more, so plan room for the whole group rather than one fish.
The Threadfin rainbowfish profile lists Pygmy Corydoras as a safe tank mate. Pygmy Corydoras schools in groups of 6 or more, so plan room for the whole group rather than one fish.
The Threadfin rainbowfish profile lists Sparkling Gourami as a recommended pairing. Sparkling Gourami schools in groups of 6 or more, so plan room for the whole group rather than one fish.
Risky or situational
From risky tank mates and broad avoid with (excluding “unsafe” below). May work with species-only setups, more water, or mature systems — read the pair page.
Angelfish reaches 20cm and is flagged predatory or as likely to eat small fish. Adult-size Threadfin rainbowfish at 3.5cm is inside that gape range. Both species defend territory. The pairing needs a long footprint and rockwork or planting that breaks the sightline between two defended spots. Angelfish is rated semi-aggressive, so expect chasing, fin damage, or display behaviour directed at Threadfin rainbowfish. Run the pair checker before stocking.
Both species defend territory. The pairing needs a long footprint and rockwork or planting that breaks the sightline between two defended spots. Betta is rated semi-aggressive, so expect chasing, fin damage, or display behaviour directed at Threadfin rainbowfish. Run the pair checker before stocking.
Both species defend territory. The pairing needs a long footprint and rockwork or planting that breaks the sightline between two defended spots. Run the pair checker before stocking.
Fish to avoid with Threadfin rainbowfish
From the unsafe list — predation, aggression, or space rules on this profile.
Tiger Barb conflicts with Threadfin rainbowfish on temperament, predation, or footprint. The juvenile size in a shop tank is not the figure that matters here.
African Cichlid reaches 15cm and is flagged predatory. Threadfin rainbowfish at 3.5cm is prey-sized for it. African Cichlid needs at least 200L, far above the 60L minimum for Threadfin rainbowfish. The tank that houses one stresses the other. African Cichlid is rated aggressive and Threadfin rainbowfish is rated peaceful. No community-style planning carries that gap.
Oscar reaches 35cm and is flagged predatory. Threadfin rainbowfish at 3.5cm is prey-sized for it. Oscar needs at least 300L, far above the 60L minimum for Threadfin rainbowfish. The tank that houses one stresses the other. Oscar is rated aggressive and Threadfin rainbowfish is rated peaceful. No community-style planning carries that gap.
Tank size and groups
- Published minimum for Threadfin rainbowfish: 60L — group minimum 8 (schooling).
- Compatibility changes when the tank is too short for turning, too little for a real school, or too warm for one species and not the other — that is why pair checks include tank context, not only temperament.
- Nearest litre hub to this minimum: 60L hub.
Plan before you buy
Pair checks for every mix, then multi-species stocking in the builder.
Filtration & heating
A 60L minimum tank for Threadfin rainbowfish needs a filter rated for at least 240L/hr turnover and a heater maintaining 25–30°C.
Similar fish (same category)
- Celebes Rainbowfish — min 80L
- Dwarf Neon Rainbowfish — min 100L
- Boesemani Rainbowfish — min 150L
- Turquoise / Lake Kutubu rainbowfish — min 200L