Oatmeal shampoo sometimes has adverse effects on some pups.
Not all fish oil is yucky. My boys love the one from Animal Essentials and it has the best/highest combo of Omega 3s. I break open the little gel capsules and put it on their kibble. We need to order more of it.
A tiny bit of organic coconut oil is an alternative. Don't go overboard with it or will cause diarrhea.
You can also try this leave-in conditioner that is popular with exhibitors:
Vellus Satin Cream (for Hair and Skin) - 4oz/118ml jar
A little goes a long way. Love this stuff and I need to order more.