In what sized tank? If you have a blue'chin or a niger trigger, you might get away with having a trigger with lions. Also, it depends on wat kinda grouper it is. Cuz groupers will eat anything that fits in their mouthes as you know, and wen you put other fish with them, you have to factor in how large the fish will eventually get (ie, make sure the grouper wont grow up to eat the lions) Also, in such a large tank, it may be difficult for you to get the dwarves to feed. The grouper and trigger are faster and will get to the food before the lions can, so theyll have to learn on a stick. And since it is such a big tank, it is harder to train them anyway. Anyway... if the trigger is docile, i think you'd be better off with a volitan or a russels lion, cuz that would never get eaten, when full grown, and they are easier to feed on the whole. Questions?