I've seen some guys that can absolutely rip through fish like crazy with one. But the rechargable ones (Piranna) and smaller FW fish.
I would go with a 120V for SW fish.
But I agree with all... just use a good sharp knife.
How many are you cleaning anyway?
~..~..~.. ><((((º>
Things done at the last possible minute are done with the greatest possible information. Procrastination is, therefore, the most efficient means of doing things.