I have a niger in my reef, he is awesome!! ... as far as trigger fish go. Compared to other species for reefs he is a pain!! I got very lucky with him, he coexists with tuxedo and a large black spiny urchin and a purple urchin, blue hermits, snails and other crabs, 3 feather duster worms, let my old large shrimp clean him and is fine with my leopard wrasse, hawkfish and various other passive and small reef fish. However he is something completely different to them. When he disklikes a certain fish (its completely random what sort of fish it will be) you can see he is a complete predator. He attacker my pair of normal occeleris clowns physically grabbed one and ragged it around like a dog toy and kills every single goby I’ve ever owned. This is the same with any trigger as you probably know, they are all predators and all complexly different. What’s safe with one isn’t safe with another even of the same species so always have emergency backup. They also make an awful lot of mess as they need A LOT of big food (full krill, shrimp, mussels etc) which is a lot messier than the others. He is also the only fish I worry about when I am not there to feed them because if he was hungry he could do a lot of damage. However I would still say nigers are great additions to reefs, they look awesome!! They swim beautifully and add a bit of cool large predator to a tank of pretty but passive fish. I would recommend them.. so long as you have backup incase it doesn’t work out for you. He is fine with all of my corals but are such aggressive feeders make sure you don’t put your food near your prized/wavy tentacle ones lol as if there is food on/ near them he will just bite out and make sure the other fish get food too!! You may have to alter feeding arrangements/quantities but you should be good! Whatever you choose enjoy