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No federal permit to keepPachypanchax arnoulti
Pachypanchax arnoulti
Fishes › Killifish and livebearers (Cyprinodontiformes) › Aplocheilidae (Panchax killifish)
Pachypanchax arnoulti is a species of aplocheilid killifish endemic to Madagascar.
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 2.3 in / 5.88 cm).
- Water: Freshwater.
- Layout: Uses both the bottom and open water: give open swimming space plus cover near the substrate.
- Availability: Rarely or never seen in the aquarium trade; expect to source it from specialists or not at all.
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 35 × 12 in (roughly 21 US gallons); space needed is rated “large tank”.
- Water: a fairly wide range, from slightly acidic to slightly alkaline, 68–82 °F, pH 6–7.5, 2–10 dGH.
- Behaviour: temperament peaceful; a shoaling fish best kept in a group of six or more; not a community fish.
- Difficulty: Moderate (Seriously Fish rating).
Short excerpts from the species profile:
- Diet: “The faeces of wild fish has been observed to contain both aquatic and terrestrial insects, suggesting it feeds both at the water surface and from the substrate.”
- Tankmates: “Relatively peaceful although much smaller fishes are likely to be predated on, and given its conservation status it's perhaps best maintained alone.”
- Breeding: “If conditions are suitable this species is not difficult to breed and will deposit its eggs among live plants, aquatic mosses, synthetic mops, etc.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Panchax killifish
Applies to most species in this group. Habitat: Aplocheilus inhabit vegetated Asian streams, swamps and rice paddies, while Pachypanchax occur in Madagascar and Seychelles freshwater habitats (lineatus, playfairii). Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- For A. lineatus use at least 75 × 30 × 30 cm, approximately 68 L (lineatus).
- Fit a close-fitting lid to prevent Aplocheilus jumping (lineatus).
- Provide dim lighting, floating plants and dense planted refuges (lineatus).
- Arrange wood and rocks into hiding places, especially for subordinate fish (lineatus).
Diet
- Quality dried food sized to the fish (lineatus, playfairii).
- Live or frozen Daphnia and bloodworms (playfairii).
- Gut-loaded wingless fruit flies or tiny crickets for Pachypanchax (playfairii).
Social life
- Keep only tankmates too large to swallow; male aggression requires space and refuges, and species tanks are preferable for conservation breeding (lineatus, playfairii).
Health watch
- Ammonia toxicity from inadequate biofiltration (fish_health).
- Parasitic skin and gill infections (fish_health).
- Nutritional deficiencies from unsuitable diets (fish_health).
Understanding the animal
About this animal
About this animal
Its natural habitat is rivers and lakes. It is threatened by habitat loss and invasive species.
Quoted from the Wikipedia article “Pachypanchax arnoulti” (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. Uses both the bottom and open water. Found in wide range of habitats: swamp whose water is clear, tannin stained, acidic, soft and deficient in dissolved substances; small creek whose water is clear, colorless, with a neutral pH, moderate hardness and deficient in dissolved substances. Feeds on terrestrial and aquatic insects and preyed upon mostly by fish-eating birds and dragonfly nymphs. |
| Water it lives in | Freshwater. |
| Climate | Tropical climate. |
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 | Pachypanchax arnoulti is a species of aplocheilid killifish endemic to Madagascar. Its natural habitat is rivers and lakes. It is threatened by habitat loss and invasive species. — 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 |
| Appearance and size | It was described by Paul V. Loiselle in 2006 with the type locality given as "Swamp draining into tributary stream of Ikopa River, flowing parallel to RN-4 at Antanimbray village, 17°10'79"S, 46°50'97"E, Betsiboka River drainage, Madagascar, elevation 246 meters". — Wikipedia (community-edited) |
| Biology | Found in wide range of habitats: swamp whose water is clear, tannin stained, acidic, soft and deficient in dissolved substances; small creek whose water is clear, colorless, with a neutral pH, moderate hardness and deficient in dissolved substances. Feeds on terrestrial and aquatic insects and preyed upon mostly by fish-eating birds and dragonfly nymphs. — FishBase |
| History and naming | The specific name of this fish honours the French ichthyologist and herpetologist Jacques Arnoult (1914-1995) in recognition of his contributions to the knowledge of Madagascar's fish fauna. — Wikipedia (community-edited) |
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; aim for the middle.
pH
Water hardness
Minimum tank footprint
Seriously Fish recommends a tank base of at least 35 × 12 in (about 21 US gallons).
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: Aplocheilus lineatus Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Seriously Fish: Pachypanchax playfairii 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.
- Merck Veterinary Manual: Management of Aquarium 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.
- 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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