My antennata is happy in a 90g, which is the same footprint as a 75g, so I would say yes they can be happy in 75g reef, they'll just eat shrimp and smaller fish. If you do your research you will not find many with an antennata long term, I've had mine for 6 years. I would only recommend this fish to someone who is willing to feed live food at least once a week. They are difficult to get eating a dead diet, when they do it is usually short lived or limited. Lions like this many times come in with internal parasites because of eating diseased fish along transport, so an effective de=worming and parasite treatment is highly recommended.