I don't even keep darts yet, but keep Mantellas and other frogs. I agree with Sarah and Melissa and pretty much listen to what they say when it comes to darts.
The thing that I think confuses alot of newbies is that they go to their local aquarium, zoo or pet store and see several species of darts mixed together. I would say there are at least 6-8 different species/subspecies and probably alot more coexisting at the Newport Aquarium. I can't say that they looked too happy, not my favorite set-up (not enough plant cover), but the frogs are eye catching with the rainbow of colors.
What it comes down to is that people want to have bright pretty pets and the more variety the better. I have heard of some oretty bad mixed terrariums. I got a whopper at the reptile show today. This is a terrarium, size unknown , housing several frog species (American tree frog species I believe), Schneider Skinks, Jeweled Lacertas, I think a newt or two, some fire bellied toads, and a few other misc lizrds. I just looked at the guy like he was crazy and told him that it didn't seem like a very good idea to me, but he says it works, i bet it doesn't.
What it really comes down to is do you want display only or do you want an eco-system? Because of the depletion of amphibians in the wild, I think it is important to take efforts towards the conservation of the natural strains. If you are mixing frogs, please keep the babies to yourself.
