Too small for a healthy school — based on adult size, bioload, and real water volume.
A 20-gallon tank is really too small for a proper group of kuhli loach — they're a schooling fish that needs at least 5 to feel secure. Step up to a bigger tank, or pick a smaller schooler.
An adult kuhli loach reaches about 4.0" and has a moderate bioload. Working from real water volume and waste output (not the old one-inch-per-gallon myth), a 20-gallon tank supports roughly too small for a healthy school of them. Because kuhli loach are schooling fish, keep them in a group of at least 5 — never just one or two. They need 73–86°F water at pH 6–7.
Build your exact stocking with the calculator → Full kuhli loach care guide →
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