Did a trawl for my marine biology course and caught a bunch of thornback rays (which have very poor survivability if you keep them out of water too long), so I was told to collect them from the fish pile first. I went to put one of the little fellas in the storage tank and got shouted at by the mouthy frenchwoman running a survey with our group because she wanted to measure the ray first before it went into the tank. So I tried to keep the thing hydrated before she got back but it stopped flapping about before she got back to me.
When I put him in the tank he just sunk like a brick, I couldn't save him.