Species profile
Lake Kutubu Rainbowfish
Melanotaenia lacustris
Peaceful
Moderate care
200 L minimum aquarium
8–10 cm adult size
Top mid
Minimum group: 6
About this species
General notes for hobby use.
Large, fast, shoaling rainbowfish. Adult groups need a four-foot aquarium with substantial open swimming space.
Water parameters
Suggested general range for long-term care.
Temperature
21–27 °C
pH
6–7.5
GH
Up to 18 dGH
KH
Not yet documented
Flow preference
Moderate
Data confidence
Verified
Behaviour
General behaviour traits used by TanksConnected compatibility checks.
Minimum group size
Minimum group: 6
Tank zone
Top mid
Territory level
None
Predation risk
Tiny fry
Bioload factor
1.3
Peaceful but active and boisterous; best with tankmates that are not easily intimidated at feeding time.
Compatibility flags
Quick cautions for common tank-planning issues.
Fin nipper
No
Plant safe
Yes
Shrimp safe
Yes
Snail safe
Yes
Cave breeder
No
Digs substrate
No
Jump risk
Yes
Natural history & care
Research-backed context for long-term aquarium care.
Lifespan
Not yet documented
Diet type
Omnivore
Minimum aquarium volume
200 L
Minimum footprint
120 × 45 cm
Accepted scientific name
Melanotaenia lacustris
Alternative names
Lake Kutubu Rainbowfish, Blue Rainbowfish, Turquoise Rainbowfish
Native range
Lake Kutubu and its drainage, Papua New Guinea.
Natural habitat
Clear lake and tributary habitats; captive fish benefit from clean, well-oxygenated water and swimming space.
Diet & feeding
Takes aquatic/terrestrial invertebrates and plant material; feed a broad omnivorous diet.
Breeding & sexing
Research-backed guidance for identifying sexes and reproductive behaviour.
Sexing
Males are more intensely blue/turquoise and deeper-bodied; females are generally duller and slimmer.
Breeding
Long-duration egg scatterer; adhesive eggs are deposited among fine plants/mops and receive no parental care.