I have been looking for something hand-operated that would dice or mince culled undesirables, not turn them into a smoothie, but more like 1/4" to 1/2" chunks. I don't know how well a standard hand crank meat grinder would work. It would probably cut it too fine and it might be hard to get whole fish crammed down far enough to allow the grinder to do it's job.
It sounds like your paste is fitting the bill, however!
I have heard several poeple saying, recently, that their fish are spitting the food out. I had fish aquariums for many years and kept some larger cichlids that would take in pellet food and immediately spit it out. This was food that they all ate on regular occasion or die...it was all they had. In some cases the pellet was too big for them to swallow, while other times the pellet was not soft enough for their liking. It was not a mater of them not liking the taste of the food, but more the physical condition. Just some old observations of mine that could apply to pond kept fish. I wonder if your BG paste is not softening up the pellets some making it more palatable? The flavor change could be the big difference too! IDK.
Mostly, I'm just trying to keep you from talking to yourself too much...LOL
