And with the fish – I know many people give their dogs oily fish 1-3x per week. I think it’s usually sardines.
About anything good and oily is good though. Sardine, salmon, krill, algae, coconut, and my dogs get flax oil as well (although they don’t absorb it as well as with fish oils). Just be a little careful not to go too overboard, as it could produce a greasy coat after a while. I know someone who gives her 50lb dogs 4 capsules of fish oil daily AND 2-4tbsp olive oil. They’re in tip-top shape and don’t stink, but leave a bit of a film after you pet them a while.
I, personally, also swear by raw eggs. My lab, who’s suffered a dull drab coat and awful skin conditions all her life, gets a whole raw egg daily. She is looking much much better.
