I'm kind of testing a theory... I found a fish place that the employees seemed to have something of a clue. What about Otocinclus? They only get to a couple inches in length and are apparently non-agressive. I'm testing it out so far with my 15 gal. with some female bettas... No issues so far, just the girls like to tease them, lol. They'll swim up and poke them with their noses and I guess they otos are high strung, they spazz and fly across the tank, lol. It's kind of like a game of tag. The girls aren't nipping them at all or anything like that. Just poking them, chasing them, then going back to chasing eachother and exploring their new home. I guess my question is more along the lines of if anyone's had complications with such a pairing?