Most setup advice skips the part that actually prevents problems: getting the foundation right before fish go in. This guide walks the fishless cycling with bottled bacteria from empty glass to stable, livable water without the usual week-two crash.
What you need
- A 20-gallon tank and a stand rated for the weight (~80 kg when full).
- Filter rated for at least 80 L/h.
- Heater (if tropical): 97 W.
- Substrate: 3 cm deep.
- Live plants and a light on a 7-hour timer.
Spending smart
You can build a solid 20-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.
Common mistakes
Adding fish during the first week, skipping the cycle, and skipping water tests are the big three. A 36% water change weekly, using Best Sponge Filter Guide: Quiet, Safe and Shrimp-Proof, prevents most problems before they start.
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 Red Pest & Bacterial Septicemia: When Fish Bleed Under the Skin walkthrough — for 24 days until ammonia and nitrite read 0 ppm.
- Test water, then add a small group of hardy fish; build up slowly.
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.
