Lizer it is
TBH I wished afterwards I'd taken a pic of the darn thing. I looked up onion maggots online but they are described as very small things while this was pretty huge - I'd say an inch long maggot. Could be larvae of a beetle of some kind if not a big honkin fly.
My friend tells me she has never seen onion maggots on the crop here. There are sometimes benefits to a miserable climate.
So I'm hoping they really don't thrive on the fish
not them.