8 Types of Killifish: A Guide to Popular Killifish Species

Last Updated: May 16, 2026

Killifish are some of the most colorful freshwater fish alive and almost nobody keeps them. Most species are not sold in pet stores.

Killifish are the best-kept secret in freshwater. The colors rival saltwater at a fraction of the cost.

Killifish are one of the most fascinating and underappreciated groups in the freshwater hobby. With over 1,200 species, they span an extraordinary range of sizes, colors, and habitats, from tiny annual killifish in African seasonal pools that complete their entire life cycle before the dry season, to striking non-annual species like the blue gularis and lyretail panchax found in planted tank setups worldwide. Many killifish are kept by dedicated specialists who seek them out specifically. Here are 8 killifish species worth knowing about.

What Is a Killifish?

Killifish are small egg-laying cyprinodont fish distributed across North and South America, Africa, Europe, and parts of Asia. Their defining characteristic is adaptability: they inhabit temporary ponds, seasonal flood plains, swamps, and slow-moving streams. Many species have adapted to environments that dry up completely between seasons, producing the annual life cycle that makes this group biologically unique among aquarium fish.

The annual killifish strategy is simple in concept and extraordinary in execution: the fish breed before the dry season, the adults die, the eggs survive buried in the substrate, and the next generation hatches when the rains return. In the aquarium, this means annual killifish eggs can be stored in slightly moist peat moss for weeks or months, then rehydrated to hatch a new generation. Hobbyists trade eggs through clubs, just as collectors trade rare stamps. It is one of the most distinctive subcultures in the freshwater hobby.

Are Killifish Hard to Keep?

Non-annual killifish are genuinely easy to keep in a properly set up nano tank. They are forgiving of water parameter variation, accept a range of foods, and stay small enough for a 10-gallon (38 L) setup. The challenges are specific: killifish are jumpers, so lids are mandatory. Males are aggressive toward each other, especially during breeding, so the male-to-female ratio matters. Most species prefer lower temperatures (68 to 75 degrees Fahrenheit/20 to 24 degrees Celsius) than typical tropical fish, which limits compatible tank mates.

Annual killifish add another layer: you are managing a species with a defined life expectancy, and breeding is part of the experience, not optional. If you are not interested in that process, annual species are not the right choice.

Care Guide

Tank Size

Most killifish are nano fish. A pair or trio of 1.5 to 2.5-inch (4 to 6 cm) species fits comfortably in a 10-gallon (38 L) aquarium. For groups with multiple males or larger species like the blue gularis, move to 20 gallons (76 L) or more to manage aggression. Larger footprint reduces conflict significantly. Some advanced keepers successfully maintain killifish in as little as 5 gallons (19 L) for a pair of the smallest species, but 10 gallons is a better starting point.

Aquarium Setup

Killifish show their best colors in a well-planted, low-flow setup. Dense vegetation, floating plants for surface coverage, and low lighting create the conditions under which these fish are most active and most visible. Dark substrate amplifies their coloration dramatically. The contrast of iridescent blue, red, and yellow against dark sand or soil-based substrate is part of what makes these fish extraordinary to look at. Keep water movement minimal. These are not strong swimmers and high flow stresses them.

Use live plants wherever possible: Cryptocoryne, Anubias, Java fern, and floating plants like duckweed or water lettuce. Floating cover is especially important for encouraging natural surface behavior and reducing the bright overhead light that keeps killifish hiding.

Filtration and Equipment

Killifish are small and produce modest waste. A sponge filter or a baffled hang-on-back filter set to low flow is ideal. If using a canister, baffle the outflow heavily. High water movement will stress these fish and push them into hiding. Most species prefer temperatures of 68 to 75 degrees Fahrenheit (20 to 24 degrees Celsius). This is cooler than most tropical setups, which limits which species can be housed alongside killifish.

Water Parameters

Most aquarium killifish prefer a temperature of 68 to 75 degrees Fahrenheit (20 to 24 degrees Celsius) and a pH between 6.0 and 7.0. Ammonia and nitrite should stay at 0 ppm. Nitrates should remain low, especially in planted setups where elevated nitrates benefit plants more than fish. Dose liquid fertilizers if the tank is heavily planted and nitrates are being consumed rapidly.

Live Plants and Decor

Live plants are essential, not decorative. Killifish use vegetation for cover, for spawning sites, and for behavioral comfort. Low-light species like Cryptocoryne, Anubias, and Java fern require minimal equipment and are ideal for killifish setups. Floating plants like duckweed and water lettuce dim the lighting naturally, which is one of the most effective ways to draw shy killifish out of hiding and into the front of the tank. Natural driftwood and rocks complete the setup.

Tank Mates

Killifish are most successfully kept in species-only tanks or with very carefully chosen companions. The lower temperature preference, low flow requirement, and breeding aggression make standard tropical community fish a poor fit. When mixed species setups are attempted, the best pairings are other cool-water, low-flow species: corydoras, otocinclus, and peaceful danios. Keep male-to-female ratios in mind: 1 male to 2 or 3 females is standard to prevent male aggression from becoming a problem.

Diet

Killifish are insectivores. In nature, they eat insects that land on the water surface and small invertebrates from the substrate. In the aquarium, live and frozen foods produce the best results: brine shrimp, mysis shrimp, daphnia, and bloodworms are all accepted. Some species refuse dry foods entirely, especially when first acquired. Offer variety and do not rely on flake food alone, particularly for annual killifish or wild-caught specimens.

Breeding

Killifish breeding varies significantly between annual and non-annual species. Both are achievable in the home aquarium.

For annual species: set up a separate breeding tank with a sunken cup or container of peat moss. Condition the male and 2 to 3 females with live food. The group will spawn over the peat within 24 hours. Remove the peat, squeeze it gently, and dry it between newspaper in a semi-sealed container for 3 to 8 weeks depending on species. Rehydrate with soft, slightly acidic water to trigger hatching. Eggs can survive in these conditions for up to 3 months. This egg-storage process is what enables the global killifish egg-trading community that makes rare annual species accessible without expensive live fish shipping.

For non-annual species: the same conditioning routine applies, but eggs are laid among plant matter rather than in substrate, and they hatch underwater without drying. Remove adults after spawning to prevent egg predation. Fry are small but accept baby brine shrimp and micro worms from hatching.

8 Types of Killifish

1. Clown Killifish

• Species: Epiplatys annulatus
• Adult size: 1.5 inches (4 cm)
• Color: Black and yellow stripes with a spectacular red and blue tail fin
• Annual or non-annual: Non-annual

The clown killifish is probably the most recognizable species on this list. The alternating black and yellow broad body stripes give it a bold look despite its tiny size, while the red and blue lyretail creates a visual payoff entirely out of proportion to the 1.5-inch (4 cm) body. Clown killifish are among the smallest killifish in the hobby and have been kept successfully in 5-gallon (19 L) tanks by experienced keepers. For most people, a 10-gallon (38 L) is the better call.

2. Gardneri Killifish

• Species: Fundulopanchax gardneri
• Adult size: 2.5 inches (6 cm)
• Color: Green, yellow, blue, and red with red spots covering the body
• Annual or non-annual: Non-annual

The gardneri killifish is a solid, accessible entry-level killifish. It is less dramatic than the blue gularis, which it resembles in pattern, but it is half the size and more suited to standard nano setups. Good for hobbyists who want a taste of the genus without the demands of larger species or annual care requirements. Widely available from specialty killifish sellers.

3. Blue Gularis

• Species: Fundulopanchax sjostedti
• Adult size: 5.5 inches (14 cm)
• Color: Electric blue body with deep red spots and stripes, ornate tail in males
• Annual or non-annual: Non-annual

One of the most spectacular killifish in the hobby. The blue gularis reaches 5.5 inches (14 cm) and is immediately identifiable by its electric blue body covered in deep red spots and stripes that sometimes overlap so heavily the fish appears red with blue markings. Males develop a long, ornate tail that extends the visual impact further. Native to rainforests of Nigeria and Cameroon. At this size, the blue gularis will eat smaller fish, so tank mate selection requires attention.

4. Lyretail Killifish (Golden Lyretail Panchax)

• Species: Aphyosemion australe
• Adult size: 2.5 inches (6 cm)
• Color: Yellow and orange base with blue overtones, red and dark orange stripes and spots
• Annual or non-annual: Non-annual

One of the first killifish to become popular in the aquarium hobby and still one of the most beautiful. Aphyosemion australe carries yellows, oranges, and blues across its body with red and dark orange spotting and enhanced dorsal, anal, and tail fins. Selectively bred color varieties exist including gold, orange, and chocolate forms. An excellent non-annual killifish for beginners to the group who want something that is both manageable and visually impressive.

5. Rachovi Killifish (Bluefin Notho)

• Species: Nothobranchius rachovii
• Adult size: 2.25 inches (6 cm)
• Color: Red and blue with a black tail fin margin
• Annual or non-annual: Annual (lives less than 12 months)

The rachovi killifish is arguably the most spectacular annual killifish in the hobby, and one of the most colorful freshwater fish of any type. The red and blue coloration is vivid enough to stop people mid-sentence. It originates from African flood plains that dry up seasonally, which is why it evolved the annual life cycle. You will not find this fish at a chain store. Source it through killifish clubs or specialty breeders. Know what you are getting into with annual care before you buy.

6. Florida Flagfish

• Species: Jordanella floridae
• Adult size: 2.5 inches (6 cm)
• Color: Silver, blue, and orange
• Unique trait: One of the few freshwater fish that eats black beard algae
• Annual or non-annual: Non-annual

The Florida flagfish is endemic to Florida and is an outlier in the killifish world: it is a native North American species, not an African import. Not the most colorful killifish, but genuinely useful as one of the few fish in the hobby that will actively consume black beard algae. Also works in outdoor pond setups in temperate climates. An interesting addition to a killifish collection for the hobbyist who wants something different from the typical African species.

7. Two-Stripe Lyretail

• Species: Aphyosemion bivittatum
• Adult size: 2 inches (5 cm)
• Color: Rainbow spectrum across males; silver with two black stripes in females
• Annual or non-annual: Non-annual

Also called the rainbow killifish. Males display an array of reds, oranges, yellows, greens, and blues against a silver base coat, all anchored by the two dark stripes running along the dorsal and ventral fins that give the species its name. Females are silver with the stripes but none of the color. Native to Nigeria and Cameroon. A genuinely beautiful fish in a well-planted nano setup and small enough to work in a 10-gallon (38 L) without crowding.

8. Golden Wonder Killifish

• Species: Aplocheilus lineatus
• Adult size: 4 inches (10 cm)
• Color: Silver and yellow base with orange and red striping across body and fins
• Annual or non-annual: Non-annual

The golden wonder killifish is native to India and Sri Lanka and is one of the few killifish regularly stocked at mainstream fish stores. It is also one of the largest species in the hobby at 4 inches (10 cm). Males are yellow with silver and blue undertones and notable red and orange striping. One important note: golden wonders are surface predators and will eat fish small enough to fit in their mouths. Do not mix with nano fish. They work in a species-only setup or with larger, robust companions.

Closing Thoughts

Killifish are not a beginner fish in the conventional sense. They require a specific setup, a reliable food source, and for annual species, a completely different relationship with the concept of fish lifespan. But for the hobbyist willing to put in that work, killifish deliver colors and behaviors that most freshwater fish cannot match. The Nothobranchius in breeding color is one of the most visually stunning freshwater fish alive. The clown killifish in a planted nano tank stops anyone who sees it. This group deserves far more attention than the mainstream hobby gives it.

Where to Buy Killifish

Chain stores rarely stock killifish. Your best options are specialty online retailers and the killifish hobbyist community.

• Flip Aquatics – One of the better online sources for specialty freshwater fish including some killifish species
• Dan’s Fish – Good source for freshwater specialty fish with honest species descriptions

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Want to learn more? This article is part of our complete Freshwater Fish Guide. Your ultimate resource for freshwater species, care tips, tank setup, and more.