Gardner's killifish
Fundulopanchax gardneri
Also known as: Blue lyretail, Gardner's killi, Nigerian killi, Steel-Blue Aphyosemion
Gardneri are those little West African killies that look like someone painted neon speckles and flag-fins onto a 2-inch fish. The males will posture and flare at each other but its more drama than damage, and they will absolutely reward you with constant spawning if you give them mops or fine plants. Biggest things to know: keep a tight lid (they jump) and do not cook them warm - they do best in the low-to-mid 20s C.
The Gardner's killifish features vibrant coloration with blue-green scales, elongated fins, and a distinctive pattern of red and yellow spots.
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Quick Facts
Size
6.5 cm
Temperament
Semi-aggressive
Difficulty
Beginner
Min Tank Size
10 gallons
Lifespan
2-5 years
Origin
West Africa (Nigeria and Cameroon)
Diet
Micropredator/carnivore - small pellets/flake plus frozen/live foods (Artemia, daphnia, bloodworms, etc.)
Water Parameters
22-26°C
6-7.2
5-10 dGH
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Calculate heater sizeCare Notes
- Keep them in a covered tank - Gardneri are jumpers and will find the tiniest gap around cables or lids.
- A 10 gallon works great for a trio (1 male, 2 females); add plants (java moss, floating plants) so the females can duck away from the male.
- They’re adaptable, but do best in cooler water (about 22–26°C) with pH roughly 6.0–7.2 (often cited 6.0–7.4) and soft to moderately hard water; stability and cleanliness matter more than chasing exact numbers.
- Feed small meaty stuff: live/frozen brine shrimp, daphnia, bloodworms, and quality micro pellets - they color up fast on variety, not just flakes.
- Tankmates: go with calm, small fish that will not outcompete them (small tetras, corys, shrimp with lots of cover); skip fin-nippers and anything fast that steals all the food.
- Breeding is easy - give them a spawning mop or a thick clump of java moss and you will get eggs; pull the mop weekly and hatch the eggs in a small container if you want to save fry.
- Watch for bullying in small tanks - a hyped-up male can harass females, so break line-of-sight with plants and keep at least two females per male.
Compatibility
Good Tankmates
- Small, chill tetras (ember tetra, neon tetra, glowlight) - they stay in the middle, dont bother the killies, and their speed keeps them from getting singled out
- Corydoras (pygmy or regular corys) - peaceful bottom crew, totally different zone, and they wont mess with the killifish up top
- Otocinclus - calm algae grazers, stick to glass and leaves, and they dont compete for the same food much
- Small rasboras (chili rasbora, harlequin rasbora, lambchop) - easygoing schoolers that dont nip fins and make the tank feel active without stressing gardneri
- Peaceful dwarf catfish like kuhli loaches - shy noodles that hang out low and mostly come out at feeding time, no drama with killies
- Amano or cherry shrimp - works best in a planted tank with hiding spots, but heads up: gardneri will absolutely snack on shrimplets if they can catch them
Avoid
- Fin nippers like tiger barbs and some serpae tetras - they will hassle the male gardneri and shred those nice fins
- Aggressive or pushy stuff like cichlids (even some dwarfs) - they stress them out and you end up with hiding killies that stop showing color
- Bettas and other fancy-finned slowpokes - sometimes it looks fine at first, then somebody decides the other one is a rival and it turns into a cold war
- Big mouthy predators like larger gouramis, angelfish, or bigger barbs - anything that can fit a killifish in its mouth eventually tries
Where they come from
Gardner's killifish (Fundulopanchax gardneri) comes from West Africa, where it lives in little streams, swampy edges, and temporary pools. That background explains a lot: they are not fussy about water the way some wild fish are, but they do act like a fish that expects cover and likes to poke around near the surface.
Most of the ones you see in the hobby are captive-bred strains and locality lines. They are generally hardy, but keep lines separate if you care about preserving a specific look.
Setting up their tank
You can keep a pair in a 10 gallon just fine, and a trio (1 male, 2 females) is even easier on the females. For a small group, I like a 15-20 gallon so everyone has their own corners.
Give them cover and they relax instantly. Think plants up top and midwater, plus a few hiding spots down low. They are not cichlids - they do not need caves - but females appreciate places to duck out of view.
- Tank size: 10 gallons for a pair or trio, 15-20 gallons for a small group
- Temp: 72-78F (I keep mine around 74-76F)
- pH: anywhere around neutral is fine (roughly 6.5-7.5 works well)
- Flow: gentle to moderate, they are not fans of being blasted
- Lighting: whatever keeps your plants happy, they do not need it bright
Lids are not optional. These fish jump. Not "sometimes" - they will eventually find the one gap for a filter cord and launch themselves through it.
For decor, I have the best luck with floating plants (frogbit, salvinia, water lettuce), clumps of java moss, and something like guppy grass or hornwort. If you want them to breed, moss and spawning mops make your life way easier.
What to feed them
Gardneri are little pigs in the best way. Most will take good quality flakes and small pellets, but they really show their color and energy when you rotate in frozen and live foods.
- Staples: small pellets, crushed flake
- Frozen: bloodworms, brine shrimp, daphnia, mysis (chop if pieces are big)
- Live (if you can): baby brine shrimp, grindal worms, microworms, live daphnia
If a new fish is being picky, try frozen brine shrimp or live baby brine shrimp for a few days. Once they recognize food, they usually convert to pellets easily.
Feed small amounts 1-2 times a day. They will act starving even when they are not, and a dirty tank is the fastest way to turn an easy fish into a headache.
How they behave and who they get along with
Males are flashy and they know it. You will see little flare-offs and chasing, especially if you keep more than one male in a tight tank. Most of it is posturing, but females can get harassed if there is only one.
- Best setup: 1 male with 2-3 females
- Multiple males: works in a bigger, heavily planted tank with broken sight lines
- They hang near the top and middle and like to patrol
Tankmates should be calm and not nippy. Avoid fin-nippers (some barbs, some tetras) and anything that will outcompete them hard at feeding time. Small peaceful fish work, but if your goal is breeding or keeping a nice line, a species tank is simpler.
They will eat shrimp babies and they will absolutely snack on tiny fry if they can fit them in their mouth. Adult shrimp sometimes survive in a heavily planted tank, but do not count on it.
Breeding tips
This is one of the fun parts of gardneri: they are very breedable without needing weird tricks. They are not annual killifish, so you are not drying eggs. They lay eggs over and over in plants or a spawning mop.
- Give them a spawning mop (yarn mop) or a thick clump of java moss
- Feed heavier with live/frozen for a week to kick things off
- Collect eggs every day or two if you do not want adults picking them off
- Incubate eggs in a small container with clean water and a tiny bit of methylene blue if fungus is an issue
- Hatch time is often around 2-3 weeks depending on temperature
If you want a steady trickle of fry, run two mops and swap one out every few days. That way you always have a batch cooking without tearing the tank apart.
Fry are pretty straightforward. Start with baby brine shrimp, microworms, or powdered fry food. Keep the water clean and do small water changes. They grow faster than a lot of people expect.
Common problems to watch for
Most issues I see with gardneri come from the same few mistakes: no lid, dirty water from overfeeding, and keeping them with the wrong roommates.
- Jumping: any opening in the lid will eventually be used
- Fin damage: usually from nippy tankmates or too many males in a small tank
- Egg fungus: happens in still, dirty water or if eggs sit with decaying plant bits
- Skinny fish: often internal parasites in new imports, or they are being outcompeted at feeding time
- Ich and other common diseases: usually after stress or temperature swings
Quarantine new fish if you can. Even a simple 5-10 gallon bare tank with a sponge filter saves you a lot of drama, especially if you are keeping a nice breeding group.
If you see a female hiding constantly with clamped fins while the male patrols, add more cover or add another female. Spreading attention out makes a big difference.
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