Pürzl's killifish

Where they come from

Puerzl's killifish (Fundulopanchax puerzli) is a West African killie from small streams and swampy, plant-choked waters. The thing to remember is they are used to warm water, lots of cover, and calmer flow than most community fish.

Most of the ones you will see in the hobby are from hobbyist lines rather than wild imports. That is good news - they are usually hardier and already used to aquarium life, but they still act like a true Fundulopanchax.

Setting up their tank

Give them a tank that is more "overgrown ditch" than "open swimming pool." You can keep a pair in a 10 gallon, but 15-20 gallons makes everything easier: steadier water, less drama, and more room for plants and sight breaks.

• Tank size: 10 gallons minimum for a pair/trio, 15-20 gallons feels more relaxed
• Temp: mid 70s F is a sweet spot for most lines (around 23-25 C)
• pH/hardness: they are flexible, but I have had the best long-term results in softer to medium water
• Flow: gentle; use a sponge filter or baffle the output
• Lighting: moderate; plants help them feel secure

For decor, think cover and line-of-sight breaks. I like a big clump of java moss or guppy grass, a few floating plants, and some wood or leaf litter. A dark substrate helps their colors pop and also seems to calm them down.

What to feed them

These are micro-predators. They will eat dry foods, but they really come alive on frozen and live foods. If you want good color and consistent spawning, feed like you mean it.

• Staples: frozen bloodworms, frozen brine shrimp, daphnia (frozen or live)
• Live treats: baby brine shrimp, grindal worms, white worms (go easy), mosquito larvae where safe/legal
• Dry backup: small pellets and quality flakes, but do not make that the whole menu

Behavior and tankmates

They are bold, curious fish with a bit of attitude. Males posture and flare a lot, and in a tight setup they can turn that into real harassment. A single male with one or two females is usually the smoothest setup.

You can keep them in a peaceful community, but pick tankmates carefully. Slow, long-finned fish get nipped sometimes, and tiny shrimp or very small fry are just food. I have had the best luck with calm, quick fish that do not compete too hard at feeding time.

• Good fits: small peaceful tetras, lampeyes, Corydoras, small rasboras (depending on temperature), peaceful loaches in larger tanks
• Avoid: finny show fish (bettas, fancy guppies), aggressive barbs, anything that will bully them off food
• Also avoid: open-top tanks (they will find the gap)

Breeding tips

They are egg layers and pretty willing once they settle in. The usual method is a spawning mop (acrylic yarn) or a dense clump of moss. They will tuck eggs into the strands, and you can collect them and hatch them separately.

• Breeding group: 1 male with 2 females reduces stress on the girls
• Spawning site: floating mop for convenience, or a bottom mop/moss if your pair prefers it
• Egg collection: check the mop every day or two and remove eggs to a small container
• Incubation: many hobbyists hatch them wet; keep eggs clean and gently aerated
• First foods: baby brine shrimp is the easy button; microworms work too for the first days

Common problems to watch for

The two big troublemakers with this species are stress and water quality swings. They are not impossibly delicate, but they do not love being bounced around by neglected water changes or a brand-new tank that is still settling.

• Jumping: gaps around filters, cords, and lids are the usual escape routes
• Fin damage: often from male sparring or cramped quarters; add plants and separate if needed
• Wasting/skinny fish: can be internal parasites or just getting outcompeted at meals; quarantine new fish and watch feeding
• Velvet/ich: shows up after stress or temperature swings; treat early and keep the tank stable
• Egg fungus: usually from dirty water or dead eggs left with good ones; pull bad eggs and use gentle aeration