Spotted...

Irony is something that you wouldn't expect to happen.. As shooting fish in a barrel is really easy, it wouldn't be ironic at all if he managed to shoot one..

The fact that he's veggie (and probably wouldn't want to kill it) makes it ironic

I wouldn't say its easy as fish are so rarely found in barrels. but i see your point, ironic how i got it wrong like i did. like having two spoons or something