In your case alot of damage. Plecs can't stand anyammount of salt and doing so will kill them slowly, not so sure on the ID sharks but being scaleless I wouldn't risk it,
on the other hand though the columbian sharks are a brackish fish which will require a large ammount of salt to live a long and happy life like they should.
These will need to be in a seperate tank to the others though and will require atleast a 90 gallon when fully grown. Rest assured there's plenty of other interesting fish you can put in there with them.
