Diamond goby is very hardy! Its not the only sand sifting goby either, im pretty sure there are a few species to choose from. Most bottom fish have high resistance to disease and parasites. These fish commonly starve in a system, but with multiple feedings of meaty foods, vitamins, and a heathy tank with a heavy pod population this has not been an issue for me. They eat A LOT!
Im not sure how housing with a Beta will be. I would wait until the beta is out of QT to QT the goby. Lets ask
@eatbreakfast