Small Fish Tank Advice

how many fish can fit in a 5 gallon fish tank?

as of right now i have a rainbow shark, 3 hatchet fish, a small platy and guppy. before this in the same tank i had two medium sized pictus catfish and a tetra and they seemed to do fine but i got rid of them for other reasons. right now they seem to be doing fine and i was told 1 gallon per square inch of fish. so i just need advice.

You are severely overstocked and need to return all of those fish. Because of that rainbow shark, you’re looking at a necessary upgrade to about a 55 gallon tank.
All fish have requirements as far as tank volume and length. Look it up please, as none of your fish’s needs are being satisfied.

Disregard that “rule”. It is outdated and very incorrect.

A 5 gallon tank is enough space for a single betta.

Fish Aquarium Juwel Lido 120