Home / Fishes / Silversides and rainbowfish / Macculloch's rainbowfish
No federal permit to keepMacculloch's rainbowfish
Melanotaenia maccullochi
Fishes › Silversides and rainbowfish (Atheriniformes) › Melanotaeniidae (Rainbowfish)
Melanotaenia maccullochi, the dwarf rainbowfish or McCulloch's rainbowfish, is a species of rainbow fish in the family Melanotaeniidae.
Care at a glance
Species-specific aquarium care
- Tank: At least 24 in long and 12 in front to back for one adult (adults commonly reach about 2.8 in / 7 cm).
- Water: Freshwater.
- Temperature: 68–77°F (range recorded for this species).
- Layout: Uses both the bottom and open water: give open swimming space plus cover near the substrate.
Calculated from this species' own FishBase record: tank size from its typical adult length and swimming zone, water values from its recorded ranges. The group guide below fills in general care.
Care guide
Species care notes
- Tank: a base of at least 24 × 12 in (roughly 14 US gallons); space needed is rated “modest tank”.
- Water: a fairly wide range, from slightly acidic to slightly alkaline, 68–86 °F, pH 5.5–8, 8–15 dGH.
- Behaviour: temperament peaceful; a shoaling fish best kept in a group of six or more.
- Difficulty: Easy (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “This little rainbowfish is ideally suited to a heavily planted setup, and will show its best colours in such surroundings.”
- Diet: “Like most of its congeners, it's an unfussy, omnivorous species, and will accept most dried, frozen and live foods.”
- Tankmates: “Very peaceful and suitable for many communitgy aquaria, given its adaptibility regarding water chemistry and relatively small size.”
- Breeding: “As with other members of the genus, this is not a difficult species to breed, being an egg scatterer, although the fry can prove somewhat tricky to raise.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Rainbowfish
Applies to most species in this group. Habitat: Rainbowfish inhabit Australian and New Guinean freshwaters, including vegetated lake shallows and the slow streams, swamps and billabongs used by threadfins. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- For Melanotaenia boesemani, provide at least 120 × 30 × 30 cm (about 48 × 12 × 12 inches) with open swimming lanes.
- For Iriatherina werneri, use a base at least 60 × 30 cm (24 × 12 inches), planted margins and gentle flow.
- Use efficient filtration and maintenance; threadfins require a mature tank with stable chemistry.
- Boeseman’s rainbowfish are sourced at pH 7.0–8.0 and 10–20 dGH; threadfins at pH 5.0–8.0 and 1–12 dGH.
Diet
- Quality dried foods; finely crush floating foods for threadfins.
- Live or frozen foods sized to the fish’s mouth.
- For threadfins: Daphnia, Moina, Artemia nauplii or copepods.
Social life
- Boeseman’s rainbowfish do best in shoals of at least 6–8. Keep threadfins in at least six, preferably ten or more, with small peaceful fish that neither nip fins nor monopolize food.
Health watch
- Ammonia toxicity.
- Nutritional deficiencies.
Understanding the animal
About this animal
About this animal
It was described by James Douglas Ogilby in 1915 when he received two samples from Mr. A. Anderson and the fish was named after the ichthyologist Allan Riverstone McCulloch.
Quoted from the Wikipedia article “Melanotaenia maccullochi” (CC BY-SA 4.0) 174
In the wild
In the wild
From this species’ own FishBase record (habitat, bottom type, water and breeding data), not its family. Good care copies these conditions.1
| Where it lives | Lives in freshwater, in rivers and streams, lakes, marshes and swamps. Uses both the bottom and open water. Inhabits lowland swamps and small streams, usually in clear, acidic waters with ample cover in the form of log debris or aquatic vegetation. Occurs at temperatures ranging from 24-30° C. |
| Water it lives in | Freshwater, 68–77 °F (20–25 °C), pH 7, hardness 10 dH. |
| Climate | Tropical climate. |
| Behavior to plan for | Breeding: open water/substratum egg scatterers. |
What this means for care
- Keep water within its wild range, 68–77 °F.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 89°F (up to 91°F in the hottest sampled areas) |
| Cool-season lows | about 65°F (down to 58°F in the coldest sampled areas) |
| Average temperature | 74–81°F across sampled records |
| Relative humidity | 76–78% on average (driest month about 71%) |
| Rainfall | about 1769 mm a year, with strong wet and dry seasons |
Measured at 21 wild occurrence records sampled against WorldClim 2.1 climate data (1970–2000 averages). Air conditions in the range are ecological context, not enclosure settings: microhabitats such as burrows, leaf litter or basking rocks can be cooler, warmer or more humid.
From the sources
From the sources
Quoted from the matching sections of reputable sources for this exact species. Specialist databases are used first; Wikipedia (community-edited, CC BY-SA 4.0) only fills gaps. Other sources are short credited quotes.
| Overview | Melanotaenia maccullochi, the dwarf rainbowfish or McCulloch's rainbowfish, is a species of rainbow fish in the family Melanotaeniidae. It was described by James Douglas Ogilby in 1915 when he received two samples from Mr. A. Anderson and the fish was named after the ichthyologist Allan Riverstone McCulloch. — Wikipedia (community-edited) |
| Where it lives | Home ranges Population dynamics Growth parameters Max. ages / sizes Length-weight rel. Length-frequencies Mass conversion Recruitment Abundance Life cycle Reproduction Maturity Maturity/Gills rel. — FishBase |
| Wild diet | Melanotaenia maccullochi is an omnivore, feeding on aquatic invertebrates, algae and terrestrial invertebrates. — Wikipedia (community-edited) |
| Reproduction | Although not much is known about these fish in the wild, breeding activities have been seen in captivity, where they readily breed. Spawning generally occurs in the early morning, the two fish will press against each other, trembling, and eggs will be deposited among the plants. — Wikipedia (community-edited) |
| Biology | Inhabits lowland swamps and small streams, usually in clear, acidic waters with ample cover in the form of log debris or aquatic vegetation. Occurs at temperatures ranging from 24-30° C. Found in clear waters of small creeks and Pandanus swamps. pH range is 5.5-7. — FishBase |
Data and studies
The numbers
The numbers
Each bar is what one source reports. Where several sources weigh in, the dashed gold band marks their average.
Adult length
Maximum recorded length. Measured as standard length (snout to the base of the tail, not counting the tail fin). Fish in home aquariums often stay smaller than wild records.
Water temperature
Range the species tolerates in nature; aim for the middle.
pH
Water hardness
Minimum tank footprint
Seriously Fish recommends a tank base of at least 24 × 12 in (about 14 US gallons).
Veterinary & husbandry research
Veterinary & husbandry research
- Two new species of dwarf rainbowfishes (Atheriniformes: Melanotaeniidae) from northern Australia and southern New Guinea Hammer MP et al., Zootaxa 2019
Peer-reviewed papers that mention this species alongside captivity, zoos, veterinary care or aquaculture. Some cover several species or mention it only in passing, so check the abstract. 170
Sources for this sheet
- FishBase (Froese & Pauly, eds.), version 24.07 Peer-reviewed researchThe global scientific database on fishes, maintained by a consortium of research institutions; every value is referenced.
- Seriously Fish species profiles Experienced keeper or breederLong-running aquarium reference written and peer-checked by experienced fishkeepers and ichthyologists; each profile covers habitat, tank size, water, diet, behaviour and breeding.
- Seriously Fish — Melanotaenia boesemani Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Seriously Fish — Iriatherina werneri Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Merck Veterinary Manual — Disorders and Diseases of Fish Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
- Wikipedia (species article) Community referenceFree encyclopedia; useful overviews with their own citations. Intro text is quoted under CC BY-SA 4.0.
- PubMed (U.S. National Library of Medicine) Peer-reviewed researchIndex of peer-reviewed veterinary, zoo and husbandry research.
- iNaturalist (captive observations) Community referenceCommunity observation platform run by the California Academy of Sciences and National Geographic; observations marked captive show animals living in homes, zoos and aquariums.
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