I have 12 in a 40g. Stream/bog setting fully planted. A behavior that i have noticed, and have not seen anyone anywhere mention is.... They burrow. Yes mine make little tunnels under the soil, right along the water. Its a rather interesting behavior but appropriate for their natural surroundings.

So, your bomber made a hidey hole id presume.

As for mixing species: the fecal and urine mix from fish and frogs will not end well and can cause more health issues than you could fathom. Also, your fishies, would be snacks for the frogs. If it moves, firebellies eat it lmao. Youd need like a tank in a tank to keep the animals and their water 100% seperate.