Gardner's killifish

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.

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

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

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.

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

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