That is truly a sad story and it puts you in a very tough position. I suppose it feels like you want to do the right thing but don't want to PO a friend over a fish. I don't envy you I think you should definitely bring it up, especially because it was native. One way to work it in would be to mention on your next fish that you are going to be careful not to gill the thing so as not to kill it, just a suggestion, good luck. Sorry about the ruined moment.
JRD