Annaliese, In the aquatic portion of my firebelly tank, I also have a land portion which helps with feeding. The fbs stay in the water but will come on land when hungry. In the substrate are isopods and springtails that they snack on from time to time. I also will supplement with fruitflies and of course crickets.

In the aquatic section I have a large rock that emerges from the water and has the effect of a feeder dish. Here I feed crickets but also Small-medium dubia roach nymphs. Whereas the crickets jump into the water, the roach nymphs will just circle around the rock surface and are perfect for the fbs as not only does more dust stay on they are also higher in calcium and lower in phosphorous than crickets.

2 out of my 5 fbs will also eat feeder guppies from the water (This took time to learn). I feed them all well one day and lightly the next two before skipping 3-4 days. This keeps them non-obese lol. Due to plants in the land portion I have a low level uvb light which will trickle down to the fbs and help with D3 conversion. I have used this setup for years with no problems. It helps greatly to have a land portion for the above reasons, however if you choose to keep it mainly aquatic a rock that serves as a feeder dish, feeder insects that are smarter and more nutritious than crickets and a low output uvb (2.0) can help.