If you mean the sucker catfish on the tank wall, that is a Sturisoma species. The usual common name is Royal Farlowella. The species in the genus Farlowella are the smaller among these loricariids, while the similar-looking larger cousins in Sturisoma can get much larger depending upon species. All of them graze algae from surfaces, including plants, and unfortunately they can sometimes damage the plants; this is especially true with more delicate leaved plants; they won't have much effect on tough plants like Java Fern or Anubias, or larger swords. But smaller plants can take quite a beating sometimes.
Byron.