I have the Rapala
Heavy Duty Electric Fillet Knife. Its an absolute tank. Cuts through anything and I totally love it.
I got the corded version because I've never had much luck with battery operated tools, but you can get the battery model if you like. I can plug it in at home or into the socket in the back of my 4Runner if I need to.
4.6 out of 5 stars on Amazon 926 ratings, can't argue much with that.
https://www.amazon.ca/Rapala-Heavy-E.../dp/B00F5EK3CG