Hardy and likes hard water. In soft, slightly acidic water like a soil tank, it actually struggles. Breeds fast, so the load grows on its own.
The largest group where none died in 90 days. Tap water · black sand · bacteria starter on day 1 · fish added on day 10 · 25% weekly water changes.
Run a 60 cm standard tank with 10 yourself →The same rules the engine uses for tankmates.
No eating or bullying either way, with plenty of overlap in temperature and pH. Fish that swim at a different level come first.
The numbers on this page come from the Water Kiwoogi simulator model; real tanks can differ.