🏠The Killifish tank: 20 L, hardware and start-up

Killifish : A 20 to 50 L tank depending on the species, gently filtered, often kept species-only with one male and two or three females. A gap-free lid is the number one safety point.

In short: 4 to 6 cm as an adult depending on the species, 20 to 50 L depending on the species, water between 20 and 24 °C. A lively, colorful little surface fish, often kept species-only with one male and two or three females. A formidable jumper requiring a gap-free lid; its lifespan varies greatly by species, often only 1 to 3 years.

20 litres minimum: why that number

For a Killifish reaching 5 cm as an adult, plan 20 real litres — and remember a big tank is more STABLE, hence easier, than a small one: parameters drift slowly, leaving time to correct. This volume suits a sturdy standard cabinet — just verify perfect levelness.

Hardware: filter, heater, lighting

On hardware: a filter cycling the volume three to five times an hour, a heater around 1 W per litre set to 20 to 24°C, backed by an independent thermometer — built-in thermostats sometimes lie, and lighting on a timer at 8 to 10 hours a day: any longer and the algae win.

Substrate, plants and start-up

Nutrient substrate under fine sand or quartz, robust plants (anubias, vallisneria, Java moss) and wood to structure the territory. Then patience: a complete nitrogen cycle (3 to 4 weeks, nitrites back to zero) before the first Killifish — the step every hurried beginner pays for dearly.

Frequently asked questions

What tank size for a Killifish?

A real 20 litres minimum — below that, parameters drift too fast to catch.

Does a Killifish need a heater?

Yes, about 1 W per litre set to 20 to 24°C, with an independent thermometer double-checking the thermostat.

The guides that apply to you

The rest of the Killifish’s gear

Bedding & habitat for related breeds and species