If you aren't doing the fish in a deep fryer and have a mess of fish, be sure you're doing them in cast iron for heat retention.

I think buttermilk is too acidic and will make the fish fall apart. I've never used evaporate milk, but don't know why it wouldn't work.

i seen a thing where they roll clams in evap. then flash fry em. i may try this cause the thought behind it was that it helped the breadin puff up and stay crisp. or some shit like that.

I say forgo the milk. I don't want my freshwater fish losing their natural flavors.

i always liked the shore lunch for deep or pan frying.

http://www.shorelunch.com/

I think crappie are best fried - and I'll let you boys argue over the perfect batter. It's all good. But I will say if you ever get tired of 'em fried, follow your favorite clam chowder recipe, add clams* galore AND a pound or two of crappie fillets, cubed into 1" or so bites. It's good stuff.

* I use canned clams, bacon and milnot + cream - pretty similar to this recipe - read the 'corrections' by Joel in comments before you cook it