Actually yes, the swordtail I used to have was initially the only one that ever picked on my snails, but recently the platies started and with too much enthusiasm. Maybe there is something particularly tastey about these snails.
I have many many snails, probably over 100 as my apple snails bred and I didn't get to the clutch fast enough. But mostly they seem to be harassing the large breading pair ie. the one that died and now the one that remains.
I will try the veggies. And maybe I am not feeding enough, though my suspicion is that I usually over feed. I have been only feeding once a day and my tank is way over capacity with young platies and all the snails and everyone else, so maybe I will start feeding more frequently.