Fish Fin Problems

[fishieluver]

My mom just bought a placostomus (I do hope I spelled that right) into my freshwater tank. She also bought me a shark and he was sitting in the plastic bag adjusting to the temperature and he was freaking out because he didn't have enough room. Well my mom let all my new fish out into the tank and the placostomus was still attached to the bag and nothing was in it. She shook him out and he seemed a little scared and went straight to the corner. When he finally moved I noticed that his fin looked like it had been ripped out and is just barely still there. I don't know much about fish but does anyone know what could happen to his poor fin?

 

[Menagerie]

First, Welcome to Aquarium Advice!
Are you sure the fin is ripped? I would be surprised that a plastic bag could do such damage. Plecos tend to stay in sheltered areas--they are notorious for hiding, not to be seen for days. If you are worried about the pleco, place him in a QT tank (if you have one) so you can monitor the damaged fin. If you do not have a separate tank, watch the pleco closely. What other fish are in your tank and how big is your tank?

 

[fishieluver]

I'm sorry I put this on the wrong forum!