Plecostomas
Hypostomas punctatus
The Plec or Pleco as it is commonly called is often sold to people to clean the algae in their aquariums. Very rarely though are these same people told how large and how quickly this little fish will grow. It will often get more than 30 cm ( a foot ) long and gets there quite quickly. Although the fish is peaceful, its sheer size makes it destructive in an aquarium as its tail uproots plants, topples rocks and ornaments and sends the gravel flying.
This fish originates in Brazil and is mainly active at night. It feeds on algae and algae tablets as well as slices of raw potato, cucumber, etc. It needs to have some natural bogwood in the aquarium as it gets a natural substance ( lignin ) from the wood which it needs for its own good health.
I personally DO NOT recommend that this fish be kept in any but the largest ( 120 gallon + ) aquariums.