Best fish for 3 gal tank

[Chad]

Most of the posts are pointing out what can't be kept in 3 gallons rather than what can.

This comment is hugely important.
Focus on what can be kept. 3 gallons is terribly small. We all pretty well know that not much can be kept in that size of tank and thrive. What can?

 

[fishyfun&fans]

Shrimp and snails maybe turn it into a brine shrimp hatchery to then feed fish in a bigger tank?

 

[Bruce Leyland-Jones]

This comment is hugely important.
Focus on what can be kept. 3 gallons is terribly small. We all pretty well know that not much can be kept in that size of tank and thrive. What can?

Beg to differ...snails, shrimp and, I believe, Chilli Rasbora may even have had a mention.
There's even a poll consistent with this.
Unfortunately, there are still some who think Betta and others would be suitable.