Unfortunately my cat has IBD and can only have chicken products, so I can't give him cod liver oil. Any other types of oils that might work?

He goes to the vet every few months for bloodwork because he's also in beginning stages of CRF, so I didn't want to take him in and stress him out just for dandruff.

He seems to groom himself okay, but he is 14 pounds and the dandruff is mostly down his spine, so maybe he just isn't grooming well there?