As for fish stiffening up and dying, perhaps they just went into shock.
I'd try to resussitate them before flushing. I once found one of my
adult bows on the floor. Although it was still moist, I have no idea
how long it had been beached. I held it under water and gently
moved it back and forth for a few minutes and presto it returned to
life. It lived for more than two years after that episode.
On another occassion I attempted to euthanise a couple lesser
specimens. I placed them in a bucket of shallow water and loaded it
up with ice. Within minutes they all turned belly up. I left them in the
bucket over night. the next morning one of them was up and around
as happy as ever. I retrieved the fish and it still lives today. I thought
it deserved to after that demonstration of toughness!!
So next time your fish stiffens up and dies, don't be too quick to flush
it away.
Chris
drews at webgate.net