I've got 4 clown loaches, 3 yo yo loaches, 2 zebra loaches, and 2 angelicus loaches that are all 2 inches or less. They are in my 29 gallon tank. Do need more than 2 of the zebras and angelicus loaches for them to act naturally and be at peace. They seem to be so now, but I keep reading the "3 or more" statement when referring to how many are needed for them to feel comfortable.