If the peas are frozen I will cook them first and then pop the shell off before feeding. Canned peas (with out salt) can be fed uncooked but I still smash them before feeding. My fish really like fresh oranges (rinse the orange and slice and feed) when they are done eating I pull the rind out and dispose of it. Succhini is another food my goldfish like, I blanch it and let it cool before feeding.
Every time I try to introduce a healthy variety of "treats," such as leafy lettuce, citrus slices, watermelon... my fish have NO interest. The only thing they go nuts over: shrimp, and garlic. I do keep trying, as I would love for them to have more variety, as well as the vitamins.