All of my 40+ species of fish eat beefheart.
I don't mix it with anything and that is almost all I ever give them. I chop it and feed it fresh to them though, no freezing. Sure the aro gets some shrimps, the plecos an occasional leaf of lettuce, some dryfood for everybody when I'm to lazy/busy to chop BH, but some 90% of what they eat is fresh beefheart chopped with a knife. Except for the aro, it does eat more shrimps.
My discus hardly touch any other food and interestingly Ashricans, that are supposed to need less protein, hardly eat anything else either.