I agree with Omni and sinibotia; Yoyos would never be happy or comfortable in a 5g tank. IMO
, the smallest tank size for Yoyos would be a 40g, and that's probably pushing it. None of mine have ever reached 10", but 6-7 isn't unusual, and they're very active fish. If you want active, schooling bottom-feeders, consider Corydoras. There are many diferent species, some very cool looking, and all are active, fun fish, with a bonus of being readily available and usually only a few bucks each unless you opt for the more rare species.