My livebearers adore peas, just lightly cooked, with the skin taken off and lightly crushed. I tried spinach on livebearers and corys last night, took them longer to demolish but all gone this morning so must have been appreciated (I know corys ate it too because they're in separate tank). Apart from nutrition and roughage, I also think it adds interest to their lives, they have to work that little bit harder to eat it, which I think is good for them.