I have a ten gallon tank with 6 neon tetras, 3 otos, and 4 Ghost Shrimp. They've all been living very happily for the last 6 months. The neons are "pretty", the otos are quick and hide a lot (sometimes in plainsight...lol) and do a great job of cleaning algae; and the Ghost Shrimp just crack me up...they also do a good job of cleaning food off the gravel and are very entertaining (my favorites). I would love to put my new very small white Crowntail in but I'd probably be overcrowding the tank and I heard that neons will nibble at his fins and he might eat my Shrimp (can't have that). So...guess I won't mess with success and keep the betta in his own place.