I find with any fish as soon as the fillet comes off it should go in ice water. Do not allow your fillets to get over 45 degrees until you cook them. Fillets should be always on ice until frozen or cooked. I splash some malt vinegar into the bag I am freezing my cats in seems to eliminate any fish taste, smell. Also soak cat fillets in water and malt vinegar if not freezing and cooking the day of the catch.