hi there,
our fish (see my sig) love frozen peas( defrost & mush up chuck in - barbs go MAD), lettuce esp romaine/dark green stuff, blanche it - pour boiling water over it for a few mins, then fix it onto a clip on tank wall, & zucchini again fix it on a little suction clip( courgette in uk) give them a little while to get used to it, try a couple of times .it took us a few attempts before our fish started to nibble nibble on the stuff & realised the stuff wasnt going to nibble nibble them. it seems to take a day or so even after blanching to soften enough for the fish to eat, but dont leave it forever as it will disintegrate & spread messy stuff all over your tank. good luck