need some advice on piranha.

I am attempting to purchase a 125 gal tank from a local man but the catch is that he currently has 4 Caribe in the tank.
I have no interest in the fish as I want the tank for my indian shovelnose who is getting to big for his 90 gal.

The issue is that I have no idea what to do with the fish as I know that they are on the invasive species list in Washington.
Do they need to be killed or is there a way to rehome them without getting into trouble?

Any advice would be appreciated

Thanks Chris

I am locking this thread because acquiring and selling or distributing of the mentioned species is illegal.  

You should refused them because taking them is illegal.  You will not be able to get rid of them legally, I would suggest euthanize or maybe the Seattle aquarium (but I doubt that will be accepted either), so euthanize is the only option.