I haven't fly fished for them and don't know anyone that has, so this is just a guess at best, so take this with a grain of salt... but you might try some small shrimp imitations and small stuff used for bonefish like mini puffs and gotchas. You might also look into some of the "mole crab" patterns they use in California for surf perch.
Where abouts are you? Folks might have some suggestions for some other stuff that's a bit easier to target and generally more willing to whack flies. .
I havent targeted either fish but I have caught a few spot on small Clousers.Usually a #2 or #4 in tan/white,olive/white or black/orange will work.Kings might be a little tougher but should be doable.Peregrines suggestion of bonefish flies and mole crab patterns should work.
Hey guys, thanks for the responses! I am in Ocean City MD. I don't know if there is anything else I could catch on a 4 wt in salt water, and a 4 wt is all I have. Maybe croaker.. but I know like NOTHING about fly fishing.
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I guess I should add that i will not be surf fishing, but fishing in the bay. There are pretty extensive flats behind Assateague Island that have skates, rays, flounder, spot, kingfish, trout, and baby bluefish.
On the way down the Eastern Shore on Rt. 13 you will go through Snow Hill MD. there is a good fly shop there I forget the name of it (Goggle can help with that) stop there. I bought flies there based on what the fella advised and used them on the Bay at Craddockville. I used my 7'9" 5wt and caught Spot and Speckled Sea Trout. You gotta fish with the tides there, ask about the tides at the shop. I believe it is fish on the incoming, on the slack, and on the way out but not at low. That is pretty much how it works here and I think that is how I fished there. It has been 16 years so you gotta cut me some slack there.................. Snow Hill Fly Shop.
Not to discourage you, but you need to be prepared to catch the largest fish in the area and a 4wt won't cut it.
A light trout rod will cast the small flies, but to be fair to the fish you need to use a rod hefty enough to land any fish you catch in a timely manner.
An 8wt will do and there's plenty that size that are reasonably priced. One of mine that I use regularly was $25
An besides, once you catch your first fish that's large enough to eat pasty little trout for breakfast, you'll have salt in your veins and may never fish for them again