I have set up tanks that crashed in week two and tanks that are still stable years later. The difference is almost never luck. This guide walks the killifish tank from empty glass to stable, livable water without the usual week-two crash.
What you need
- A 10-gallon tank and a stand rated for the weight (~40 kg when full).
- Filter rated for at least 40 L/h.
- Heater (if tropical): 125 W.
- Substrate: 2 cm deep.
- Live plants and a light on a 9-hour timer.
Step by step
- Rinse substrate, add it, and hardscape before filling.
- Fill slowly to avoid clouding; start the filter and heater.
- Cycle the tank — see the lowering nitrates guide guide — for 35 days until ammonia and nitrite read 0 ppm.
- Test water, then add a small group of hardy fish; build up slowly.
Common mistakes
Adding fish during the first week, skipping the cycle, and skipping water tests are the big three. A 21% water change weekly, using a solid angelfish care: graceful centrepieces for a community tank, prevents most problems before they start.
Next steps
Once stable, layer in more plants and a few peaceful tank mates. Keep a log of parameters; a tank you measure is a tank you can trust.
Spending smart
You can build a solid 10-gallon tank without premium gear: a reliable filter, a second-hand stand, and easy plants do most of the work. Spend on the heater and test kit, where cheaping out costs fish.
