Very very simple--you can use any kind of fish you like. I had some swai the night I did this, but you can use tilapia, catfish, cod, trout, red snapper...anything you like.
I didn't take any photos until the end because it was an afterthought since this is really that simple.
Start by filling a heavy-bottomed pot with about 2 inches of frying oil--vegetable oil is fine, peanut oil works well, too. Heat this to about 375-400. While your oil is heating up, put a little more than a cup of flour on a plate, and a little more than a cup of flour into a vessel that'll hold liquid. Season it with salt, pepper, and Old Bay. To one, add a whole 12 ounce beer and whisk it together. Prepare your fish--pat it dry, slice it into pieces that'll suit your purpose--making fish and chips? Slice it into strips. Making sandwiches? Sandwich sized portions. :)
When your oil is hot, take the fish, dredge lightly in the flour, then dunk it into the beer batter, and then back into the flour for a good coating before slipping it into the oil. (Do not overcrowd your pan--it will lead to greasy fish! Blech.) Cook for a few minutes on each side until it is perfectly golden brown, pull it out and drain it on a tea towel or paper towels or newspaper or a paper bag or or or, well, whatever. Serve. :)
This was my husband's sandwich....I may or may not have eaten mine while I was cooking....