yea 2 FBTs is all the amphibians i have. i would love to put a fish species in the tank but its mostly frowned upon because of the toxicity of the toads, plus i heard they attempt to eat the fish out of the water too. U must have gotten your toads at petsmart because the place i got them from also housed them with small red crabs. my tank setup is pretty simple but i think my next tank change will have some dimension (got great ideas from the forum). I just have garden stones on the bottom, a floating lillipad for feeding, a waterfall-filter, a bridge that i placed up against the glass so the toads can get some height if they want, a small castle for no reason really, some plastic leaves hanging from the wire lid, and a leaf-tub that suctions to the glass. Its a 10 gal + is mostly water. Anyway, id say forget the sand, thats defintly a no-no due to the risk of eating it along with their food. It runs the possibility of causing impaction and subsequently killing your toads by accident. Id also say trade your heater in for a thermometer. As long as theres an efficient light source + out of the elements of winter (away from drafty windows or you have the heat on in your home) they should be fine. I have a thermometer + a heat-bulb just incase their temp goes below 65 but its important to keep an eye on their temp, wether its winter or summer. Substrate on the other hand i cant help u out with much because i dont use it but a lot of other people do so maybe they can be more helpful. goodluk!

P.S. Stay away from mealworms!! Their exoskeleton is difficult to digest and they attempt to chew their way through an intestine once eaten. I learned that the hard way years ago when i kept 3 American Toads. My smallest toad was as hard as a rock the morning following a feeding day, frozen in a "swallowing" position like he had somthing caught in his throat. (RIP AL)