Hi richard,your ST sounds just like my IT,i did the same as you when he was about ten inch but i stopped at about 40,but then he just looked round for the little pellets i put in for the others,so he was obviously not full lol
Here he is waitng for some more,lol;
My 8" has eaten 30 in a sitting and I'm sure he's not a 1/3 as big as that ST. I think that your fish will be fine. 100 massivore is only a big handful. For a big fish thats nothing.