I feed mine freeze dried crickets on a regular basis. they mash up well for feeding the smaller guys, but when the big ones get a whole bug I've seen them come out almost whole, but drained of all color. pretty gross.
I used to feed my oscar mayflies too, he'd chew them up and spit out the wings.
nothing wrong with fish meal. when fish eat each other, they get the bones, guts, etc. all part of good nutrition. but just peas and bugs? I'd be very surprised if there wouldn't be nutritional deficiencies without a greater variety.