PlanetCatfish.com

I currently have two tanks they hold the following:
tank 1
10" gibiceps pleco
synodontis eurupterus 7"

Tank 2
18" gibbiceps pleco
12" synodontis notatus.
28" fire eel

i am planning to rehouse all my fish together in a 8ft tank my question is will my catfishes get on if they are put together?

You may find that the two Gibbiceps do not like being in close proximity to each other. I get chasing taking place in a 16ft aquarium with this species!
Pete

I agree; most territorial catfishes that are bigger should be kept single, OR as a group preferably bigger than 5, so the aggression can spread.
With two; you can get the "infamous Ping till you Pong" effect. It almost always ends with losing one fish.

You might do your Fire-eel a great pleasure with that tank; it's the biggest Mastacembelid I know, and it can double the length it already has.