Chiz
if the fish isn't bleeding, then what you experienced
is quite normal, what's stresses a fish is when you start poking it while it lies on the bottom
if it is dying it will tend to float, not sink to the bottom.
However should it be bleeding from it's gills then please put it out of it's misery
and take it home. They do taste good
and if you have to pay , then so be it. Just don't be
one of the wankers who try to hide fish they have unwittingly killed
just avoid paying a couple of quid
Not fair to anyone.
Sandy