Moshe says to the warden, "I did not catch these fish, they are my pets. Every day I come down to the water and whistle and these fish jump out and I take them for a swim only to return them at the end of the day."
The warden, not believing him, reminds him that it is illegal to fish without a license, and a heavy fine is levied for illegally fishing rare fish. The fisherman turns to the warden and says, "If you don't believe me then watch," as he throws the fish back into the water.
Avi the Warden says, "Now whistle to your fish and show me that they will come out of the water."
Moishe turns to the warden and says, "What fish?"