German Blue Ram aggressive at feeding time

[datasaurus]

We added a German Blue Ram to an existing community tank about a month ago, and he's recently started getting aggressive at feeding time -- he spends more time chasing and nipping other fish than he seems to spend eating. The other fish are still getting enough food (they come right back, rather than running away and hiding), but I'm concerned about the stress and possible injuries. And I don't like having a bully in what was a peaceful tank!

It's a 40-gallon tank, moderately planted. The main other fish are a dozen cardinal tetras, a half-dozen cherry barbs, and two powder-blue dwarf gouramis (female). We primarily feed flakes (frozen brine shrimp as a weekend treat), and when we got the GBR we added a half a sinking wafer. He mostly went for the wafer, and after a few weeks he started guarding the wafer. The dwarf gouramis would come munch on the wafer some, and he'd mostly maneuver around them. But if a cherry barb came near the wafer, even if he wasn't actively eating, he'd chase them off. So far, not too bad.

But then the GBR started getting aggressive more generally at feeding time. We'd put in the flakes and wafer together, he'd follow the wafer down, but then he'd swim back up near the top of the tank and start chasing the barbs and nipping the gouramis (I've never seen him bother the cardinal tetras). He's not doing much feeding at this time, mostly chasing. He'll pursue the barbs for some distance, not just shoo them away from "his area," and will sometimes even charge after a barb that's over in a corner. He'll nip at the gouramis' sides, though they don't run off (though one of the gouramis recently got an abrasion/wound on her side that might be from him nipping her?).

After a minute or two he'll calm down, even though there are still some flakes drifting about and the other fish feeding on them. I haven't seen him act aggressive at other times, only when the food is added.

We tried no wafer and extra flakes this week, in case he was just taking "guarding his wafer" too far. At first it seemed like it was working, but after a couple days he's back to being a bully again. Any advice?

[Guppysnail]

This sort of sounds like he may not be getting adequate nutrition. By that I do not mean he is not getting enough but something in his diet is missing. My GBR do better on granules containing spirulina and algae. Kens fish food 1 mm green granules is their favorite. Mine hate flake and barely eat any of it. They let it float past them. 
I do notice my GBR eat considerably more than other similar size fish. I also worked on teaching them surface feeding. The granules float for a minute and they come top side and get their fill. When they were in a community tank they filled up first then ignored everyone else. Whenever I cut back feeding they would be crabby with one another and the other inhabitants. 
Feeding twice daily instead smaller portions rather than just one time a day also kept my kids from being crabby.