I went, I saw but I didn't buy
There doesn't seem to be a hassle free way to bring the fish back.
If you box it up into a styrofoam box and check it in, I heard that there wouldn't be much problem, but I am worry that, firstly the styrofoam box might not be able to take the baggage handling and also I don't know if the fish can take the handling esp. the bigger fish.