I feed peas weekly to my bettas, little plecs and anyone else interested.
For larger fish, can just squash between your fingers and drop them in to sink.
(Smaller fish can get large pea pieces caught in their throats and choke - at least 2 WCM that I know of have, one of mine being a victim.)
And just thought I'd mention, my baby Bristlenose's absolute favorite anything seems to be cooked frozen baby Brussel Sprouts, although we're (sob) out now.
And I'm assuming my elusive dwarf plec's as well, as I don't think anyone else in that tank could make such a mess of them.
And cooked asparagus is always popular, though haven't had recently.
But if you ever have any in, you'd probably have tried them on your fish anyway.
And I'm sure you've tried cucumber, which is a favorite (sometimes) with my otos as well, who normally don't bother with veg.
And be warned, if you haven't tried it yet, saving fully-cooked chunks of yam for your fish is best done when your planning a tank clean right away anyhow.
That, and people look at you funny when you say you're saving bits of your supper for some of your fish.
Totally weird...
Gives me the typos...