Good herbivore/algea eater for my tank?

[Kryten]

Just wondering what people think would be good for my situation. I have a 24 gal nano with corals, an occellaris clown, yellow watchman goby, green wrasse, and purple pseudochromis. Getting a lot of different kinds of green things growing and need something to help keep it in check. Could be fish or invert, doesn't matter as long as it will be compatible and do the job. I've had emerald crabs in the past but they have died quickly - I suspect the wrasse.