feeding lettuce/spinach

i use veggies a supplement for my oscars, feed cucumber or zucchini every 3rd day or so.i leave it in over night and remove it the next day in which time theres usually nothing left.
I use a good pellet as their staple, veggies as a supplement and krill or shrimp as treat.

Peas are my favorite to feed my goldfish because they will play with them for awhile. If you boil some peas, or microwave a cup of water with them in it and then peel the shells off the peas, the goldfish will chew on them and eat them. I know they sell clips that you can clip lettuce to the side of your tank with (they have little suction cups on them) and i wouldn't leave the lettuce in there for more than a day. When I feed my goldfish peas, thats the only thing i feed them that day. Have fun!