That is what I would be worried about, primarily.When they're $1.00 each at Petsmart I buy all they have and quarantine them in a 10g tank, for a couple of months. The most so far has been 22. Apparently they were happy. After I took 22 out to put into my 75g community I had three left.
For a 10g community tank, I suggest 3 - 5 depending on the rest of the fish. Otos don't produce the bio-load of a large molly, but they do have to digest a lot of algae.
Exactly wht I was was going to say.Actually none, they really only thrive in much larger, well-established planted tanks.