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No federal permit to keepSplash tetra
Copella arnoldi
Fishes › Tetras, piranhas and pacus (Characiformes) › Lebiasinidae (Pencilfish and splash tetras)
Copella arnoldi, commonly known as the splash tetra or the splashing tetra, is a species of tropical freshwater fish belonging to the family Lebiasinidae.
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 1.3 in / 3.36 cm).
- Water: Freshwater.
- Temperature: 77–84°F (range recorded for this species).
- pH: 6–8.
- Hardness: 5–12 dGH.
- Layout: Uses both the bottom and open water: give open swimming space plus cover near the substrate.
- Diet: A predator: feed meaty foods sized to its mouth (frozen fish, shrimp, worms); it will eat tankmates that fit in its mouth. 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
- 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 4–7.5, 1–8 dGH.
- Behaviour: temperament peaceful; 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: “Best kept in a densely-planted aquarium or paludarium with some overhanging vegetation, roots or branches important if you wish to raise fry alongside the adults (see 'Reproduction').”
- Diet: “A micropredator feeding on tiny invertebrates and other zooplankton in nature, especially at the water surface.”
- Tankmates: “Peaceful but somewhat unsuitable for the general community aquarium.”
- Breeding: “Displays an interesting reproductive strategy in which spawning and egg deposition occurs on overhanging vegetation above the water surface.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Pencilfish and splash tetras
Applies to most species in this group. Habitat: Common pencilfish and splash tetras inhabit vegetated South American streams and tributaries, with Copella also entering flooded forest. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- N. beckfordi needs a base of at least 18 × 12 inches; C. arnoldi needs at least 36 × 12 inches for long-term care.
- Use dense planting, floating plants, branches and leaf litter for shade and broken sight lines.
- Use gentle filtration for pencilfish; provide well-oxygenated water with slight surface agitation for splash tetras.
- For breeding C. arnoldi provide about 4 inches between water and cover, plus overhanging spawning surfaces.
- Use a biologically mature aquarium; splash tetras are sensitive to chemistry swings.
Climate & lighting
| Water | 69.8–80.6°F |
Diet
- Dry foods small enough for their mouths.
- Daily small live or frozen Artemia nauplii, Moina or grindal worms.
- Small gut-loaded fruit flies or crickets for C. arnoldi.
Social life
- Keep N. beckfordi in groups of 10 or more and C. arnoldi in mixed-sex groups of 8–10; choose peaceful small companions. Male pencilfish spar, so provide visual barriers.
Health watch
- Water-quality stress in immature aquaria.
- Nutritional deficiencies from unsuitable food sizes or limited diets.
- Freshwater white spot and other skin/gill parasites.
Understanding the animal
About this animal
About this animal
It is native to South America, and has been introduced to the island of Trinidad. The fish is named in honor of German aquarist Johann Paul Arnold (1869–1952), who collected the type specimen.
Quoted from the Wikipedia article “Copella arnoldi” (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. Feeds on worms, insects and crustaceans. |
| Water it lives in | Freshwater, 77–84 °F (25–29 °C), pH 6–8, hardness 5–12 dH. |
| Climate | Tropical climate. |
| Wild diet | Hunting macrofauna (predator). |
| Behavior to plan for | Breeding: clutch tenders. |
What this means for care
- Keep water within its wild range, 77–84 °F.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 90°F (up to 92°F in the hottest sampled areas) |
| Cool-season lows | about 70°F (down to 68°F in the coldest sampled areas) |
| Average temperature | 78–80°F across sampled records |
| Relative humidity | 79–83% on average (driest month about 76%) |
| Rainfall | about 2351 mm a year |
Measured at 109 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.
| 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 | Deposits eggs on underside of objects above the water surface. Male in water splashes the clutch periodically. In the aquarium, male and female swim vertically to the surface, flick their tails and leap up to a leaf. — FishBase |
| Biology | Occurs in groups at the surface of small creeks with clear waters. Also found in ponds where it is found together with Rivulus. Feeds on Ephemeroptera larvae and ants; also on worms, insects and crustaceans. — 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.
Typical adult weight
Average adult body mass in each database (FishBase gives the maximum recorded weight).
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.
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.
- Nannostomus beckfordi — Seriously Fish Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Copella arnoldi — Seriously Fish Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Disorders and Diseases of Fish — Merck Veterinary Manual Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
- Parasitic Diseases of Fish — Merck Veterinary Manual 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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