No no no, it's just a precaution to make sure you have a fish with which to hit someone, should the need arise. The ideal practice is certainly to use a live fish, and the Talisker Rebbe (zikhrono levilbul) was makpid to carry a small fish tank at all times to make sure this was possible under any circumstance. That said, most poskim allow processed fish lekhathila as long as it's visually identifiable as fish by a katan of average seafaring ability.