fire bellied toad owners...

I'm setting up a 65 gallon paludarium, close to 50/50% land water ratio, i will be transferring my espei rasboras and tetras (about 15 all together i think) and would <i> love</i> to have some oriental fire bellies in the tank as well. i know the upkeep and general keeping of frogs, and have read much about the fire bellies. I was just wondering from a general consensus if anyone keeping them in a paludarium with smaller fish has had many issues of toxicity level in the water harming small fish or having the small fish become snacks to the frogs...
any input is appriciated as i need to know what im building my land mass for before i can start construction on it...

i'm used to doing about a 30% water change every week on my 29 gallon and was planning on doing the same with the paludarium....i'm probably going to run either a wet/dry filter or a canister filter once i decide on a design
that and i was only thinking about having 3-4 in my 65 gal., so i dunno if not having as many frogs to water/land as i could would help keep any toxins down or not.

it's gonna be a few months as i plan on setting it up when we move into the house (transitioning will be much easier) but i'm pretty excited about it. i knew i wanted frogs but i was having issues finding which ones i could keep well, ideally id have poison dart frogs...but i'm not sure im up to it. and of course the red-eyes are amazing but for a first time frog owner i'm not willing to risk it.
thanks for the help...i'm all ears