I dont see any health testing on your website..or maybe i missed it
Do you health test your dogs for hips, elbows, patellas, thyroid, etc. ?

Are you interested in one of my pups or just looking for a debate? I am not much into playing games online. I don't know any Dane breeders who test patellas and very few do elbows. I do what I feel is necessary.

As for an all fish diet. Bad idea. A dog can not get everything they need from fish alone.
Carrots do not provide any nutrition what so ever to a dog unless they are ground to a pulp to break open the cells that hold the nutrients. Canine teeth are not designed to nor can they break open the cells to release the nutrients. That goes for all vegatables. Totally useless unless pulped or juiced.
My dogs like them to, but I am aware they get nothing from them. Dogs are carnivores and their teeth are designed to eat raw meaty bones. This is why you never see a dog raiding a garden or grazing a corn field.
It can take awhile with detox, but you might look into other reasons for the oily skin. Thyroid testing is a good place to start.