Raw feeders, please answer my questions about fish

OK, I have a few questions for you raw feeders about fish. I have read that oily fish are best because of the omega fatty acids they provide. Could someone please provide a list of oily fish? Are smelt considered oily?

I've also read that fish shouldn't be fed more than once or twice a week, but I'm unclear on how much of the once or twice-weekly meal should be fish. The entire meal? Half of the meal? Just one tiny smelt once a week? I'm asking these questions relative to both the cats and the dogs. My largest dog, Tasha, gets 1-1.5 lbs of meat and bones/day. Should I be giving her 1-1.5 lbs of fish once a week?

How long do fish keep when frozen? I have come across a guy who has a LOT of smelt from last spring's smelt run that he's trying to sell right now. This smelt is frozen, but there's so much of it that it could last me years. As long as it remains frozen, how long will it remain feedable to the dogs and cats?

I'm a bit confused about this fish thing. Please clarify this for me.

Thanks!

Laurie