Home / Fishes / Killifish and livebearers / Dusky millions fish
No federal permit to keepDusky millions fish
Phalloceros caudimaculatus
Fishes › Killifish and livebearers (Cyprinodontiformes) › Poeciliidae (Livebearers)
The dusky millions fish, (Phalloceros caudimaculatus), also known as the caudo, the leopardfish or the one-spot livebearer, is a species of fish native eastern and southern Brazil, northern Argentina, Uruguay and Paraguay.
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 1.4 in / 3.5 cm).
- Water: Freshwater (tolerates brackish).
- Temperature: 68–75°F (range recorded for this species).
- pH: 7–8.
- Hardness: 9–19 dGH.
- Layout: An open-water swimmer: needs long, open swimming space with few obstacles.
- Diet: FishBase classes it as a carnivore.
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
- Water: a fairly wide range, from slightly acidic to slightly alkaline, 61–72 °F, pH 7–8, 5–25 dGH.
- Behaviour: a shoaling fish best kept in a group of six or more; suited to a community tank.
- Difficulty: Moderate (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “A gently filtered, heavily planted set-up suits it best, and it seems to be sensitive to fresh water.”
- Diet: “Unfussy and omnivorous, it will accept most foods offered.”
- Tankmates: “Should ideally be maintained in a species tank.”
- Breeding: “Being a livebearer, it is quite easy to breed.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Livebearers (guppies, mollies, platies and swordtails)
Applies to most species in this group. Habitat: Warm streams, ponds and brackish waters. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- Planted tanks with gentle flow; mollies appreciate harder, slightly brackish water.
Diet
- Flake foods with plant matter, plus live or frozen foods.
Social life
- Peaceful community fish; keep more females than males.
Health watch
- They breed constantly; plan for fry or keep single-sex groups.
Understanding the animal
About this animal
About this animal
It has also been introduced to Australia, Malawi and New Zealand; primarily for mosquito control, but also as escapees from the aquarium trade. It has been reported as having adverse ecological effects in areas where it has been introduced.
Quoted from the Wikipedia article “Dusky millions fish” (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 and brackish water, in rivers and streams. Inhabits swamps and drains of Perth metropolitan area, Western Australia. |
| Water it lives in | Freshwater / brackish water, 68–75 °F (20–24 °C), pH 7–8, hardness 9–19 dH. |
| Climate | Tropical climate. |
| Behavior to plan for | Breeding: internal live bearers. |
What this means for care
- Keep water within its wild range, 68–75 °F.
- It tolerates or needs brackish water; check salinity needs before setup.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 84°F (up to 88°F in the hottest sampled areas) |
| Cool-season lows | about 49°F (down to 44°F in the coldest sampled areas) |
| Average temperature | 63–72°F across sampled records |
| Relative humidity | 74–79% on average (driest month about 71%) |
| Rainfall | about 1467 mm a year, spread fairly evenly |
Measured at 401 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 | The dusky millions fish, (Phalloceros caudimaculatus), also known as the caudo, the leopardfish or the one-spot livebearer, is a species of fish native eastern and southern Brazil, northern Argentina, Uruguay and Paraguay. It has also been introduced to Australia, Malawi and New Zealand; primarily for mosquito control, but also as escapees from the aquarium trade. It has been reported as having adverse ecological effects in areas where it has been introduced. The females of this species grow to a total length of 6 cm, while males remain smaller. — 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 |
| Reproduction | After about 24 days gestation, 10 to 50 young are born. — FishBase |
| Biology | Inhabits swamps and drains of Perth metropolitan area, Western Australia. — 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.
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.
- Merck Veterinary Manual: Management of aquarium fish Zoo, university or veterinaryThe Merck Veterinary Manual: a standard veterinary reference written and reviewed by veterinary specialists.
- Merck Veterinary Manual: Types and features of aquatic systems Zoo, university or veterinaryThe Merck Veterinary Manual: a standard veterinary reference written and reviewed by veterinary specialists.
- Merck Veterinary Manual: Nutritional diseases of fish Zoo, university or veterinaryThe Merck Veterinary Manual: a standard veterinary reference written and reviewed by veterinary specialists.
- Wikipedia (species article) Community referenceFree encyclopedia; useful overviews with their own citations. Intro text is quoted under CC BY-SA 4.0.
- 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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