Lost track of this thread; nice to see it still going. The hand-feed video is exactly what was needed, more useful and interesting than another goldfish-down-the-hatch one.
My apologies if my earlier comments were taken as "disheartening", wasn't the intention. I just wanted to suggest a move in this direction, i.e. actually doing and documenting something new, useful, and in all likelihood healthier for the fish. Judging from the apparent size of your gulper, it should be able to easily handle silversides now; they are very slender and elongated, with no inconvenient spines or projections. Actually a pretty poor design, if your goal is to avoid being eaten, since they slide down like a cold beer on a hot day...
They gutload very easily; a small slit in the abdomen, and several pellets, tablets, etc. can be tucked inside. Best to push them into the opening and then back towards the tail; when the fish is swallowed headfirst, this prevents them from popping out as the body is squeezed into the predator's mouth. Algae tabs would work great. I've also filled gelatin capsules with powdered supplements...more for reptiles than for fish...and they are a convenient way to load this type of substance into a silversides, earthworm, shrimp, etc.
