They do get to about a foot, they get terribly aggressive and territorial and will latch onto and hurt large slow fish. I wouldn't recommend buying one
II had a couple golden algae eaters. They are great when they are small because they really get your tank clean. When they are small you can put them with almost any fish. When they are older I would put them with more aggressive fish. They do grow slow.
Golden AEs are a type of Chinese AEs. As mentioned, they will probably eat some algae when small but as they get older, they quit eating it and can become very aggressive. They will also try to suck the slime coat of other fish, especially slow moving, flat-bodied fish like angel fish and gouramis. If you want a good algae eater, look for Siamese AEs. They are great community fish. Just make sure that you don't get one of the look-alikes. See my species profile for the differences.