Join Date: Jun 2010
Location: Northern Virginia
I don't think you'd have a problem with the betta in this situation. However, keep in mind that ADFs can be extremely challenging to feed in a community tank situation. They are almost completely blind, so do not expect to just drop in a sinking pellet and for that to be the end of it. All the rest of the fish in the tank will consume every last bite before the frogs even know what's going on. They're not good for scavenging for uneaten food on the bottom, either--so don't expect them to eat the flakes your schooling fish miss.
When I had an ADF with a betta (which I now regret) the only way I could feed him was to get a live blackworm between my fingers and stick my arm in the tank to wave the worm in front of his face for a few seconds. This was the only way I could get him to eat with the betta present. If you have a tank with only ADFs, you could designate a feeding dish. Put the food on the dish in the same place every time, and the frogs will eventually learn to go to the same place when they smell food. However, all of your other fish will quickly learn this trick, so it won't work in a community. You should give some serious thought to how you're going to pull off daily feedings if you're determined to have ADFs.
The otos are another issue, to me. All otos we see in the pet store are wild caught--this means that they aren't adapted to live in aquariums like many other species, such as domestic betta splendens. Many otos eat exclusively algae and refuse all prepared foods like sinking pellets. Of all the algae that you might grow in your tank, they only eat a few very specific kinds. Otos are only recommended for mature tanks with a constant supply of algae--a new setup will not have the algae needed to support these otos and many of these fish are at the point of starvation before you even bring them home because of the conditions in the pet store.
Have you considered a school of pygmy cories or kuhli loaches instead of otos and ADFs? To be honest, a couple of nerite snails will do a better job of cleaning algae than the otos, and they aren't nearly as sensitive. Nerite snails can't reproduce in fresh water, so you needn't be concerned by a potential snail takeover.