Clown Plecos clean the aquarium really well. They are a little sensitive to some things, but I guess that everything is sensitive to something. I had 1 about a year ago and it cleaned all and everythingin my aqaurium:) It died though do to some aquarium salt:( My dad bought some aquarium salt caus ethe people at petland said it was great for plecos, but it just killed :( It deid after about 1 month. other then that they are great for 10 gallon aqauriums. If you want a good cleaning animal that doesnt eat guppies ( wel cant catch them) is the Apple Snail. You have to feed them some letuce and other veggies though. I have 2 in my 10 gallon fry aquarium. I hope this helps:)