Community Fish Tank..Who is the culprit?

[DillD]

I have a 20 Gallon fish tank with the fish below in it. My one cherry barb Male fins look like they have been bitten at. All the other fish are fine and perfect. I am trying to find out who is being the aggressive on. What do you guys think>?

- 7 Harelquin Rasboras
- 2 Cherry Barb (male+female)
- 2 Furcata Rainbow (male+female)
- 2 Algea eating shrimp
- 2 Otto Cats (*Not chinese algea eaters)