Hey, fishman, how's it going?? My Otos eat the green algae and microscopic clear algae that we can't see, but more like feel (slimy!!). I got 4 Otos, put them in an algae infested tank and it was clean within 3 days. The only thing you need to be careful about is that these fish eat constantly and will die without enough algae. Plus, you need to acclimate them carefully. The last time I got Otos I just dumped them in. Not a good idea. This time I kept the bag in the tank, but every 15 minutes I put in a tablespoon of water from my aquarium. I did this until the water had doubled in volume and everything worked out great!! I can't wait until I get my new male Betta today!! I have the tank set up (10g) and the only reason why it says that a Betta is in there is because I reserved him. But I'll see what other options they have. I'm getting him in 2 hours once the store opens. XD *can't contain excitement!!*