I had otos with my betta in his 5 gallon, however he thinks he needs to chase them. But I also have them with my girl and she is fine with them. So it really depends on the betta's personality. The otos did a fantastic job cleaning the tank though.
They need to be in at least groups of 3. Groups of 2 will do, but they are much more active with 3 or more.
Dijon: Blue mustard gas hmdt plakat male
Little Girl (LG): Blue crowntail female
No name yet: Purple/pink/white delta tail male
No name yet: Red and silver halfmoon male
RIP Storm, Flair, Marina, Flash, and Sterling... I miss you guys so much :(