First off, this needs to be moved to the appropriate forum. Secondly, tasseled filefish get up to 12in. so I personally don't think it belongs in anything under 125g for long-term care. If you wish to purchase anyways or plan to upgrade in the future, they seem to enjoy meat items such as clam, krill, fish, shrimp, etc. and in the wild will consume algae (feed nori as a mix) and other invertebrates including gorgonians, sponge, and I wouldn't doubt some coral. I think you might be pushing the issue quite far in getting all 3 fish to tolerate each other in just a 72g in the long run.