Clown Killifish Care Guide

The clown killifish is a tiny, peaceful, surface-dwelling nano fish of about 3.5 cm, instantly known by the male's red-blue 'rocket-exhaust' tail. It harms nothing, but two facts govern keeping it well: it is bite-sized prey for most ordinary community fish, and as an obligate surface fish it is a determined jumper that needs a fully sealed lid.

Clown Killifish at a glance

The sourced figures the welfare engine uses to judge Clown Killifish — the parseable key facts.

Where it comes from

Epiplatys annulatus comes from the coastal lowlands of West Africa — swamps, slow streams and small rivers in southern Guinea, Sierra Leone and Liberia, shallow heavily-vegetated water with barely any current. That biotope is the care sheet. The soft, acidic, often tannin-stained swamp water tells you to keep it soft and acidic with leaf litter and dim light; the shallow, surface-rich habitat is why it lives at the very top and wants floating cover and gentle flow; and although it is tropical by origin, a few coastal localities are even mildly brackish. It carries the old genus name Pseudepiplatys on plenty of shop labels and in older books — same fish, now folded back into Epiplatys.

Did you know?

• The male's caudal fin flares red, blue and white like a rocket's exhaust, earning the fish its other name, the Rocket Killifish.
• For decades it was the only member of its own genus, Pseudepiplatys, before being merged back into Epiplatys — so old books list the same fish under the former name.
• It is a non-annual African killifish: unlike the celebrated 'annual' killies that hatch, breed and die in a single rainy season, it lives several years and breeds continuously, with no drying-out diapause needed.
• Despite tropical origins it does well — and may live longer — in cool, even unheated room-temperature tanks.
• Some of its wild coastal homes are mildly brackish, unusual for a soft-acid nano fish.
• Conservation status is IUCN Least Concern (assessed 2020).

Tank size — and why

Five US gallons is the practical floor for a small group in a dedicated, well-covered nano tank, and 10 gallons or more — roughly a 45 by 30 cm footprint — is better and matches what a proper group of eight to ten really wants. The fish is tiny and very low-waste, so bioload is not the driver: the minimum exists for surface area, room for the group, and stable water. Because it lives at the top, length and surface area matter far more than height.

As a guide, a 20-gallon tank comfortably suits about 8–12 Clown Killifish as a single-species display, leaving room for tankmates.

See it to scale

Adult Clown Killifish reach only about 3.5 cm (1.4 in) long — close to the size they are sold at, so what you see is roughly what you get. The catch is the group: a proper shoal still needs about a 5-gallon tank, around 41 cm long.

Adult size is sourced; tank length is approximate for a standard 5-gallon aquarium.

Water parameters in practice

Soft and acidic is the load-bearing requirement: aim for pH around 6.0–6.5, with the species tolerating a wide 4.0–7.0, and keep the water soft at roughly 4–8 °dKH. Hard, alkaline tap water is the main chemistry mistake and also blocks breeding. Temperature is the nice surprise — despite tropical origins it is one of the few tropical nano fish that does well in cool, even unheated rooms; about 22–25 °C is the sweet spot, it sits happily across 19–26 °C, and cooler water can actually lengthen its life by slowing its metabolism. An old FishBase note calling it 'very difficult to maintain' reflects dated practice, not today's consensus; in soft, stable, covered water it is reasonably hardy.

Diet & feeding

A surface micropredator with a tiny mouth, so food size and surface delivery matter more than for most community fish. Offer tiny floating foods — crushed flake, micro pellets, freeze-dried daphnia — backed by small live and frozen fare such as baby brine shrimp, daphnia, moina, grindal and micro worms, cyclops and fruit flies. Many individuals are reluctant on dry food and clearly prefer live, so keep some in the rotation. Feed small amounts once or twice a day, and make sure the slow, timid killi gets its share before faster fish clear the surface.

Gear & setup

A tight, fully-covered lid is the single most important hardware fact — as a surface fish it will slip through filter cut-outs and feeding gaps, and jumping out is its most common avoidable death. Pair that with gentle flow (a sponge filter is ideal), dense planting and especially floating plants for surface cover and security, and a dark substrate with leaf litter to mimic the swamp and intensify colour. A bright, bare, high-current tank is exactly wrong for it.

Temperament & behaviour

Essentially peaceful and loosely gregarious — a top-dweller that hangs near the surface as a relaxed social group rather than a tight tetra-style school. The only friction is mild male-to-male competition over display, which is managed by keeping more females than males; it is never seriously aggressive and is not a fin-nipper. It is a 'peaceful predator' in one narrow sense: it will hunt anything tiny enough to eat, such as insect larvae and baby shrimp. With a good group, extra females and a planted, shaded surface it is confident and colourful; too few fish in a bright open tank leaves it shy, hidden and faded.

Group & social needs

Keep it in a group — best of all eight to ten or more — with more females than males, aiming for roughly one male to every two or three females so rival males don't spar. It is gregarious rather than a strict shoaler, but it needs the company to stay bold, visible and well-coloured. It is not a centrepiece fish to keep singly.

Compatible tank mates (preview)

A short, engine-cleared shortlist — the species TankStocking's welfare engine clears with Clown Killifish and that suit its size and temperament best. Tap any to load the pairing in the planner.

• Amano Shrimp — Peaceful temperament, similar adult size.
• Assassin Snail — Uses the bottom zone, peaceful temperament, similar adult size.
• Black Neon Tetra — Uses the midwater zone, peaceful temperament, similar adult size.

A note on the shrimp and snails here: Clown Killifish is peaceful and generally invertebrate-safe — but almost any fish will take very small shrimplets given the chance, so give shrimp dense cover (moss, leaf litter) if you want a colony to grow, rather than expecting every baby to survive.

This engine-cleared shortlist is Clown Killifish's tankmate surface for now — a dedicated tank-mates guide can follow for high-demand species.

Breeding & sexing

Easy by killifish standards and a good first killi to breed, with no dry diapause needed since it is non-annual. Sexing is simple: males carry the brilliant red-blue rocket tail, longer fins and a larger body, while females are plainer with a clear tail. Give a mature, soft, acidic, warm tank (around 24–26 °C) with fine-leaved plants, mosses or spawning mops at the surface. They are serial spawners, laying a few eggs in vegetation every few days rather than one big batch; eggs hatch in about 9–12 days. The key gotcha is fry care: adults leave their offspring alone, but older fry eat younger ones, so separate cohorts by size and start them on infusoria or vinegar eels before baby brine shrimp.

Lifespan

Roughly 2–5 years; plan for about 3, with good care and cooler temperatures pushing towards 4–5. It is a non-annual killifish that lives several years and breeds continuously, unlike the seasonal killies that die when their pools dry. The main shorteners are jumping out, predation by oversized tankmates, hard or unstable water, and slow starvation in a tank where faster fish win the food.

Common mistakes

• No lid, or a gappy one. It will jump out and die on the floor — seal every opening.
• Putting it with 'normal' community fish. Angelfish, gouramis, cichlids and bigger barbs or tetras will simply eat a 3.5 cm fish. Only calm, similarly tiny tankmates are safe.
• Hard, alkaline tap water. It needs soft, acidic water; hard water stresses it and blocks breeding.
• Too small a group or too many males. Keep eight to ten or more with more females than males.
• A dry-food-only diet in a bright, open tank. Many specimens want live or frozen food and a planted, shaded surface, and slowly starve or hide otherwise.
• Strong filter flow. Use a sponge filter or other gentle flow.

Signs of trouble

• Colour fading, especially males losing their tail colour.
• Hiding below the surface and refusing food.
• Clamped fins and skittish, washed-out behaviour — often too few fish or too bright a tank.
• Thin, sunken bellies on new imports — buy plump, active fish.

Is this fish right for you?

Don't buy it if you can't fully cover the tank, if you keep or plan to keep any fish big enough to eat a 3.5 cm fish, if you have hard alkaline water you can't soften, if you want a single centrepiece fish, or if you only feed flake and want a hands-off open community tank. On stock quality there are no dyed or balloon morphs in normal trade; the main issue is thin, transport-stressed or starved imports, so buy plump, active fish with good male colour and quarantine them. Mix it only with calm, peaceful, non-predatory tankmates its own size, or keep it in a species tank.

Common questions

What can live with clown killifish?

Only calm, similarly tiny fish — celestial pearl danios, chili rasboras, Norman's lampeye killifish, pygmy corydoras and snails are good choices, plus adult dwarf shrimp with cover. The question to ask is 'what will eat it?', not 'is it aggressive?', because at 3.5 cm it is prey for most ordinary community fish.

Do clown killifish jump?

Yes — as an obligate surface fish it will jump through any gap. A tight, fully-covered lid with filter cut-outs and feeding holes sealed is mandatory, and jumping out is its single most common avoidable death.

How many clown killifish should I keep?

Eight to ten or more, with more females than males — roughly one male to every two or three females. It is gregarious and needs the group to stay bold, visible and colourful; it is not a fish to keep singly.

Can clown killifish live in an unheated tank?

Often yes. It tolerates cool tanks across about 19–26 °C and can live longer in cooler water, though the breeding sweet spot is warmer at roughly 24–26 °C. Stable, soft, acidic water matters more than chasing a high temperature.

Do clown killifish eat shrimp?

Adult dwarf shrimp are generally fine, especially with plenty of cover, but clown killis will eat baby shrimp and shrimplets. If you want both, establish the shrimp colony first.

Sources & confidence

Sources & confidence (9 species)

These back the Clown Killifish figures and the previewed tank mates above. Each figure is read from the TankStocking species database (v2026.06); below is the care reference behind it and how confident we are in that data. Confidence reflects the source quality, not whether any pairing is safe. Full source list and the welfare model are on the methodology page.

• Clown Killifish Epiplatys annulatus — Seriously Fish (Epiplatys annulatus); Aquarium Co-Op high confidence
• Amano Shrimp Caridina multidentata — Aquarium Co-Op amano shrimp care; Aquadiction high confidence
• Assassin Snail Clea helena (Anentome helena) — The Shrimp Farm (theshrimpfarm.com/posts/assassin-snail-care) high confidence
• Black Neon Tetra Hyphessobrycon herbertaxelrodi — Seriously Fish / Aqua-Fish (Hyphessobrycon herbertaxelrodi) high confidence
• Black Phantom Tetra Hyphessobrycon megalopterus — Seriously Fish (Hyphessobrycon megalopterus) high confidence
• Bronze Corydoras Corydoras aeneus — Seriously Fish (seriouslyfish.com/species/corydoras-aeneus) high confidence
• Cardinal Tetra Paracheirodon axelrodi — Seriously Fish (seriouslyfish.com/species/paracheirodon-axelrodi) high confidence
• Celestial Pearl Danio Celestichthys margaritatus — Seriously Fish (seriouslyfish.com/species/celestichthys-margaritatus) high confidence
• Checker Barb Oliotius oligolepis — Seriously Fish — Oliotius oligolepis (https://www.seriouslyfish.com/species/oliotius-oligolepis/) high confidence

Care-guide sources (6)

This guide synthesises the references below; where they disagree, the range and the disagreement are noted in the text above. The figures in the key-facts box are read from the TankStocking species database (v2026.06). Full welfare model on the methodology page.

• FishBase — Epiplatys annulatus — authority (Boulenger 1915), family Nothobranchiidae, max 4.0 cm TL, temp 23–25 °C, range (Guinea/Liberia/Sierra Leone), trophic level 3.2, IUCN Least Concern (2020), non-seasonal, 'buy at least 8–10… relatively gregarious', incubation 9–12 days, 'older fry do eat the younger'
• Seriously Fish — Epiplatys annulatus — synonyms incl. Pseudepiplatys annulatus, coastal-swamp biotope (warm soft acidic, some brackish), 30–35 mm SL, temp 20–26 °C, pH 4.0–7.0, 45×30 cm tank, diet (Artemia/Daphnia/Moina/grindal), peaceful but not ideal community fish, sexual dimorphism, relatively easy to breed, 9–12 day incubation
• Wikipedia — Epiplatys annulatus — Boulenger 1915 (orig. Haplochilus annulatus), full synonym list incl. Pseudepiplatys, range, type locality (Maka, Moa River), common names, IUCN Least Concern
• Aquarium Co-Op — Care Guide for Clown Killifish — up to 1.4 in (3.5 cm), 2–3 yr (cooler extends it), 5-gal nano min, 67–80 °F/19–26 °C unheated OK, tiny floating + slow-sinking foods, tight sealed lid (jumper), top-dweller, 1 male : 2–3 females, good tankmates (CPDs, lampeye, chili rasbora, pygmy cory, snails), eats baby shrimp, sponge filter, heavily planted
• Fish Laboratory — Clown Killifish — 1.2–1.4 in, lifespan 3–5 yr, 5-gal min, 68–79 °F, pH 4.0–7.0, carnivore prefers live food, top-dweller, groups of 8–10, predation warning ('may become the dinner'), breeding on vegetation, hatch ~2 weeks, sexing
• Shrimpy Business — Clown Killifish Care — up to 1.4 in, lifespan up to 5 yr, 5 gal recommended / 10 gal+ preferable, 67–80 °F, pH 4.0–7.0, hardness 4–8 dKH, top-dweller, group 8–10, 'peaceful predator', micropredator diet, Corydoras-compatible, 9–12 day incubation, male dimorphism

More on Clown Killifish

Related guides on TankStocking — each scored by the same welfare engine as the planner.

This care guide is a sourced planning reference, not veterinary advice — individual fish, filtration and maintenance all matter. Cycle the tank, test your water, and observe your fish. How TankStocking works →