Where did you read that from? Be wary that some sites say that in order to sell fish; in reality, a minimum would be a 20 gallon long because of how active they are and their size (especially for skirt tetras) but there are tons of other options that would work nicely instead ^^I read that both of them's minimum tank size is FIVE gallons, though.
Haha, you'd be surprised about the fish that are available to the hobby! Do keep in mind that some are common and some are a bit rarer; of course, the rarer you go, they tend to be harder to keep (and more expensive haha)KinsKicks that list is HUGE! I literally thought no more than about a dozen types of fish could fit!