black and dalmation mollies eat it off the glass. Loaches eat the actuall plants!! (they think it's funny). And coreys eat algae tabs, but I don't think they eat much from the tank...well not mine.
Algae is an imbalance in something...overfeeding, insufficient water canges, too much nutrient. Make sure you realize the cause or else it is an endless battle. You may be able to solve it without the addition of more fish. You may not be able to solve it with fish at all.
For instance, if it is an overall green tank, I'd do a black out and not get another fish. Good luck!