Join Date: Jun 2009
Location: Honolulu, Hawai'i
Nah, I don't think so. They're messy for a fish their size, but they're still pretty tiny. If anything, they'll make your nitrates rise more quickly than before, so you may have to do more water changes that you normally would on a tank with just a single betta, but nothing too crazy.
And, when I added my otos to my main tank, there was no mini-cycle. The bacteria will eventually catch up with the bioload.
55 gal - 1 betta, snails, some shrimp, various plants
20 gal - 1 betta, snails, shrimp, java moss and fern