No photo yet
Sign in to submit the first photo
Threadfin Rainbowfish
Iriatherina werneri
Animalia›Chordata›Actinopterygii›Melanotaeniidae
📍 New Guinea / Australia
The threadfin rainbowfish is a delicate, striking fish with males displaying long, flowing finnage tipped in vivid colour. It is a micro-predator that requires calm water and very small live or frozen foods. Best kept in species tanks or with the smallest, gentlest tankmates.
Care Guide
Diet
Threadfin rainbowfish are micro-predators requiring small live or frozen foods such as baby brine shrimp, micro worms, and daphnia nauplii. Feed small portions once daily, offering only what can be consumed in a few minutes. High-quality frozen foods and occasional quality micro pellets can supplement live foods, but live prey should form the diet's foundation.
Behavior
These delicate fish are peaceful but skittish, requiring calm water conditions and minimal disturbance. Males display elaborate, flowing finnage and engage in gentle courtship displays. They are mid-water swimmers that prefer to school with their own kind and become stressed in turbulent environments or with aggressive tankmates.
Breeding
Breeding in captivity is possible but challenging and rarely achieved by hobbyists. They require pristine water conditions, dense vegetation for egg scattering, and very small live foods for fry. Fry are extremely tiny and difficult to rear, making successful breeding uncommon in home aquariums.
Tank Mates
Similar size, peaceful temperament, and compatible water parameters make them ideal companions
Tiny, non-aggressive, and thrive in similar soft, slightly acidic conditions
Peaceful invertebrates that won't compete for micro foods and add biological balance
Small, gentle algae eaters that occupy different water zones and have compatible care needs
Generally peaceful but may occasionally chase threadfins; requires careful observation
Common Diseases
Ich (White Spot Disease)
White spots on body and fins, rapid breathing, flashing against surfaces
Raise temperature gradually to 28-30°C, perform daily 25% water changes, use aquarium salt or ich medication; maintain excellent water quality
Fin Rot
Frayed or deteriorating fin edges, discoloration at fin bases
Improve water quality immediately, perform frequent partial water changes, use antibacterial medication if severe; ensure pristine conditions
Stress-Related Illness
Loss of color, clamped fins, lethargy, refusal to eat
Reduce water movement, minimize disturbances, ensure adequate hiding spaces, maintain stable parameters; avoid aggressive tankmates
Malnutrition
Fading colors, stunted growth, hollow belly appearance
Provide varied live foods daily (brine shrimp, micro worms, daphnia), supplement with quality micro pellets; feed 2-3 times daily in small portions
Community Photos
0 photosPhotos are added when members log a tank with this species and upload a photo in their tank journal. Add your own tank to contribute.
No photos yet — add a tank with Threadfin Rainbowfish to be the first!
Sign in to vote.
Tips from the community 💡
0 tipsReal experiences, care advice, and keeper notes. Finn learns from these too.
Sign in to share your experience.
No community tips yet — be the first to share your knowledge!
Tanks keeping this 🐟
Kept by 1 hobbyistCommunity tanks featuring Threadfin Rainbowfish.
Quick Facts
- diet
- Micro-predator – baby brine shrimp, micro worms, daphnia nauplii
- lifespan
- 3–5 years
- max size
- 4 cm (1.6 in)
- tank size
- 10 gallons minimum
- school size
- 8+
- temperament
- Peaceful but very delicate – avoid fin-nippers
Water it likes
- ph
- 6.5–7.5
- ammonia
- 0 ppm
- nitrate
- <15 ppm
- hardness
- 5–12 dGH
- temperature
- 75–82°F (24–28°C)
Stats
More Melanotaeniidae
Boesemani Rainbowfish
Melanotaenia boesemani
Dwarf Neon Rainbowfish
Melanotaenia praecox
Eastern Rainbowfish
Melanotaenia splendida
Lake Kutubu Rainbowfish
Melanotaenia lacustris
Lake Tebera Rainbowfish
Melanotaenia herbertaxelrodi
Millennium Rainbowfish
Glossolepis pseudoincisus