This is an old thread, but in light of there being so many negative outcomes posted so far, I wanted to add a success story
I've had ADFs in several community tanks over the last 5 years or so with zero problems whatsoever. It is totally doable, but it takes some extra care. Here's the factors that I think will give you the best success:
1) Don't expect them to eat pellets, flakes, or sinking tablets. It is a very rare frog that will eat them. Frozen and live foods they will eat with gusto and will be fat and happy frogs in no time.
2) You absolutely have to target feed them. They have horrible eyesight and find their food mostly by smell. My fish are constantly stealing food from right in front of the frog's faces if I don't distract the rest of the tank first with their own food before feeding the frogs. I put the frozen cubes (chopped in half if they're too big) into a turkey baster, suck up some tank water into the tube, put my finger over the end and shake till the cube thaws out. Then I hold the end of the tube in front of the frog's face and squeeze the food out so it just barely hangs out the end and dangles just in front of the frogs nose. They'll grab it within a few seconds. I usually tap the front of the tank a couple times before putting in the turkey baster so the frogs have an audio cue to connect with feeding time. Once they hear it they come right to the front if they're hungry.
3) Don't keep them in big tanks. I had my frogs in my 75 gallon tank for a while and usually the only time I saw them was at feeding time because they would hide from all the activity. They also have to work harder to get to the surface to breathe in the taller tanks. Worn out frogs that are nervous from all the larger community (both in number of fish and fish size) = hiding frogs.
4) Keep a few of them, not just a single frog. Frogs seem to like company, and if you have both males and females they'll tend to grapple and sing to each other. Having company tends to make them more bold about not hiding all the time.
5) Consider ways to give them dimmer lighting, whether this is in the form of having floating plants, tall plants, or using moonlights. They tend to shy away from the bright lighting used in planted tanks. That doesn't mean they shouldn't have live plants, quite the contrary. They do appreciate having live plants to either climb to the surface or to hang out under and will be more active and social if you offer these things rather than keep them in an unplanted tank.
Given the right care and tank, frogs can add quite a bit of comedy and interest to a community. I love my frogs, and am constantly laughing at the odd poses I find them in when they're front and center begging for food. They're very comedic klutzes and I'll hear them singing to each other on most nights. Don't be discouraged!
