CichlidFish.com - Fish That Think.

I have a 100 gal. with:
1 red devil (5-6 inch)
1 oscar(6-7 inch)
1 convict (2-4 inches)
1 jack dempsey (4-6 inches)

The red devil and the Jack are the most ravenous eaters i have seen. The jack is moreso than the red devil, he will eat any and all of what i put in the tank, leaving just leftovers for the other fish.

I use several kinds of food: frozen bloodworm cubes, chiclid pellets, and dried tubifex worms. They really like the frozen bloodowrms, and the chichlid pelets, but they pretty much dont eat the dried tubifex worm cubes. Usually I put 2 cubes of bloodworms in(one on each side of the tank) and the jack and devil take care of those quik, then i put pellets in until they dont get eaten anymore. Is this a good feeding method?

any other foods i should add to their diet?

What you're feeding now isn't bad.  If they don't like the freeze-dried tubifex, try freeze-dried krill.  Feed them as much as they'll eat in 2-4 minutes.  They'll decide what that amount is.

thanks