Did you remember to add dechlorinator and was the temperature about the same as the tank? If so, they might just be stressed from the water change, hopefully they'll calm down, just keep an eye on them.
I'm not sure how many peas per fish; I doubt they'll eat a half one let alone a whole one, although I have mostly small fish so maybe Mollys would be different. How many fish do you have? They'll probably just pick at it a few times if they even like it (some fish don't). I'd prepare maybe 4 peas (I put mine in a plastic container with some water, add a drop of dechlorinator because I'm paranoid and microwaver them for a few minutes then remove the skins; you might need to add some cold water b/c it'll be very hot lol), and then smoosh them with your finger so they split in half or quarters and then drop them in. Remove whatever they don't eat after an hour or so.