Six is the minimum: schooling fish and why we say it
22 June 2026 · 5 min Header photo — neon tetra school
Three schoolers do not school. They hide. The group is too small to share risk, so each fish treats the tank as unsafe and fades against the glass.
Six is the lowest number that reliably produces the loose mid-water band you are buying the fish for. Eight to twelve is better in a 75-litre tank. The extra fish are not decoration; they are the condition the species needs.
If the tank cannot hold six, pick a species that does not school.