I’m assuming that is gymnothorax tile? If so I’ve kept them on multiple occasions, awesome fish! Glad to see your using sand, they are super voracious eaters and I had one die from ingesting gravel. Only advice I have is choose your tank mates carefully, they can eat surprisingly large fish. Bigger scats, monos, archers, datnoides/coius would all be good tankmates.
other common “brackish” fish such as needle nose gar, mudskippers, butis butis, larger gudgeons, etc. would likely get eaten. Had a 12” gar get bitten in half by one of these morays about a decade ago.
have fun and keep us posted with pictures!