I am thinking of setting up a reef tank. I already have 65lb of sand and 35lb of rock, a light, and I have my eye on a 48x18x12 super shallow tank, maybe with a 29g sump. My favorite saltwater fish based off of youtube and what I see in LFSs are the damselfish, but the only info I find online seems to say they are a bad idea, mostly because they are aggressive. They don't seem to be any more aggresssive than their cichlid/sunfish cousins from the videos I see. Is there any good info on care for them? Line of sight blocks, keeping only damsels, avoiding similarly colored fish? Or are they really impossible to keep?