The solid parts I guess you could try, but I would skip the really soft parts in the middle as they would probably make a mess. Wash them first. Tomatoes you can probably feed raw, but harder veggies like carrots or zuchinni should be microwaved for 20-30sec to soften them up. Obviously if you try something and the fist don't like it, net it out so it doesn't sit in the tank and rot.
meats-wise, it is often a bad idea to feed meat a person would eat (beef, chicken, etc.) to fish. Fat content is much higher than what a fish would naturally eat, so better to feed a high quality pellet or frozen food.
the way i see it, if a fish wouldnt normally eat a salad in the wild, or fruits, then i won'tfeed it, the exception being fish that need fresh plant matter (like algae-eating fish) where i don't have the proper supply of algae.
