This sand eel was foul hooked while jigging for striped bass with an AVA Diamond Jig. It was about 6 inches long, and pretty skinney.
The sand eel is a small, slender fish, also know as a Sea Lance. Sand Eels can often be found along the Northeast coast where there is a sandy bottom. In recent years large populations of sand eels have shown up along the LI and NJ coasts in the fall. They can be found throughout the water column, but more often near the bottom as they dig into, and hide in the sand. Sand eels are a favorite food of striped bass.
Sand eels are a delicate fish and are difficult to keep alive, so they are not usually used as a live bait. Dead or frozen sand eels are often used as a bait when drifting for fluke, but striped bass don't seem interested in frozen or dead sand eels.
Fortunately sand eels can be imitated rather effectively using narrow metal lures and sparsely tied teaser flies.
Metal diamond jigs are good lures to use when sand eels are the predominate baitfish. One of the best example of metal diamond jigs are AVA's, shown in the photo below.

Ava's come in numerous sizes. Show above are from left to right:
007, A 17, A 27, A47 and A67.
The A17 and A27 are the most popular sizes used by surf fishermen, as they are a good match to the size of sand eels. However to get more casting distance, especially into the wind, an A47 is often used.
The A27, A47, and A67 are most popular when jigging from a boat, the weight being dictated by sea state and drift rate.

AVA and Teaser
Often fishermen use both an AVA and a teaser, with the teaser mounted maybe 20 inches above the AVA on a dropper loop, or seperate leader.
Both the AVA and the teaser look like sand eels. The heavy AVA allows you to cast further, and on retrieve it stirs up the bottom, and draws some attention. You may catch a double header.
Good teaser choices include sparsely tied streamer type flies and soft plastic lures.
Another metal lure to use when the prevalent bait is narrow bodied, like sand eels, is a Deadly Dick, shown below.