Seems all recipes call for bonito fillets to be skinned.
I tried this recently but attempts to remove the skin with a fillet knife were destroying the fillets. I used a method that is successful with flathead - cut through the fillet to the skin and lay the blade along between the fillet and the skin, pulling the skin in a sawing motion, rather than cutting with the knife. Having said that, I don't usually remove flathead skin either.
I abandoned the attempt and fried the fillets with the skin on. The skin shriveled away to nothing and the fillets came out great.
Is there a particular method for skinning bonito? Is it necessary?