I have a Gold Nugget Pleco in my tank and I love him dearly -- he's my favorite fish! -- but trust me when I say that getting a pleco like the one you want (or I have) will not make your tank cleaner! They are very, very cool to look at, but very, very dirty to keep up with. I'd bet that my one pleco produces about 90% of the (visible) waste in my 20 gallon tank. In addition to creating a mess (if you get my drift), they also stir up the gravel when they swim, which can make the water cloud up. I also got the pleco thinking that he would help cut down on the algae, but he mostly likes rasping on the wood and eating algae tablets. Talk about a freeloader! (Or maybe an expensive-loader?)
Anyhow, I've heard good things about otos, but haven't kept them myself. Personally, I've been amazed with our Siamese Algae Eater. You have to be very careful when buying one, because other fish are frequently mislabeled as SAEs, but I was amazed at the SAE's ability to clean up the algae in my tank.
I bought my SAE at 2" when I had just had an amazing algae bloom due to new (much stronger) lighting. While he didn't eat the longer algae on the plants, he completely consumed all of the algae from the large pieces of bogwood (the lush green mossy-looking stuff), plus a bunch of the black algae from the plants, heater, etc., in about four days! That aquarium looked like a whole new tank! I can't rave enough about him, and he's definitely a workhorse. Four months later, I haven't had another problem with algae, outside of some episodes of cloudy/green water. By the way, the SAE is now almost 4" long -- he must be keeping up with whatever's trying to grow in there!
Anyhow, I can't recommend this fish enough. Like I said, be sure to get a true SAE -- the black stripe should run the length of his body to the fork in his tail. Other fish sold as SAEs can get aggressive as they age; the SAE is quite peaceful. Mine has fallen in with two swordtails about his size, and now he's just one of the boys.
Here are two websites that give the SAE's distinguishing characteristics:
http
/www.aquatic-gardeners.org/cyprinid.html
http
/www.petresources.net/fish/article/sae.html
Good luck with whichever fish you choose!
-- Pamela