pangasius help!

[Mr Exotic]

I have a rather large hifin pangasius. I just wanna know what fish I can keep him with. He's about 55 cm long. I kept yhim with some 70cm fire eels,30 cm mountain spineys, parrot fish,frontosa,40cm oscars,and 3 20cm arrowana in a 680l tank. He eats everything. Like everything . Ate all my fish I only have one fire eel left. When I put my finger in the tank he goes and bites it. I need to know what fish I should get to mix with him that won't get eaten. I'm thinking of a motoro stingray and a couple red tail cats