Using a deep fryer for fish
Yes, Yes, and Yes.

Citations:


If you plan on offering seafood as well as other proteins you will want a separate cooker to prevent the dreaded fishy taste transfer.
Typically, once you fry fish in the oil, it tastes like fish, which might not be a flavor you want in your fried chicken.
A fish and chips concept risks not only rancid flavors from frying oil overdue for a change, but also unwanted odors—and more importantly proteins—from fish and breading that could have cross-contact with the fries.