I'm a newbie aquarist, so I'm not really the one to answer this question. But from personal experience, I can say that mine lived with a school of neon tetras, who left him entirely alone, and also with a handful of guppies, who also got along fine with him. Hornwort is a great plant to help with cycling, and also grows like a weed, is very inexpensive, and requires very little care (when it gets too long, just snip off the top and you have another bunch of 'new' plants for the tank). My ADF loves it, as did the other little fish that lived in there with him. I even have 2 Mollies and had no trouble with the frog. I think you'd be alright with any peaceful schoolers here. . . hang on for a more expert opinion, of course.
HOWEVER, again in my experience, it can be quite difficult to make sure the frog gets enough food without over feeding the fish! They're slow eaters, and I pretty much feed Speckle by hand most of the time - but even so, it's quite impossible to keep bloodworms or brine shrimp from floating away and into the mouths of other fishies. . . so I'm not sure if a small school of fish would really be a fantastic choice, since they might get too much food, and you'd really HAVE to be very careful to make sure froggy gets enough. Most people say that 'species only' tanks are best, and I can see why now that I've had my frog for a month in the main tank. His 5 gallon tank should arrive any day now, and in the future I may consider a single betta, but it will be SO much easier to keep frogs alone. Another option you might want to consider is getting one of those screened dividers for your tank, either for feeding time, or so that you can have 5-10 gallons for the frog(s) only, and the other side for fishies :) They're about $10 at PetSmart.
Yet another thing to consider is that whenever you get a new creature, it's advised to keep them quarantined for 4-6 weeks so that they don't spread sickness to the rest of the tank. If you don't HAVE a quarrantine tank, it might be a good idea to get all the frogs you want to keep at the same time and from the same tank. . .
But I'm still a total newbie, so I'll be watching to see what our resident expert has to say on this :)
Last edited by Chesh; 03-08-2012 at 02:03 PM.