No harm in dropping a few zucchini / lettuce pieces in as well, it may take a few attempts before they eat them but once they do, they will eat them readily.
Trick is, is to add them into small pieces during regular feeding, observe the behavior.
Peas, carrots are generally not a good idea for JD as they do not offer a lot for them. The convicts might eat them.
If you add these do not overfeed them until the fish are eating them, otherwise vacuum or remove any pieces left over. When I had my JD and convicts I used something similar to this
, which allowed me to remove the pieces if uneaten. Make sure it is plastic with hardly any metal parts. For lettuce, a small rock can be used to hold the leaf in position.
to what you are feeding now.