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 breeding tank setup from empty glass to stable, livable water without the usual week-two crash.

What you need

Step by step

  1. Rinse substrate, add it, and hardscape before filling.
  2. Fill slowly to avoid clouding; start the filter and heater.
  3. Cycle the tank — see our columnaris: the cotton-mouth bacteria guide — for 26 days until ammonia and nitrite read 0 ppm.
  4. 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 35% water change weekly, using the how to set up a quarantine tank (and why you need one), 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.