Treasures in Fan-Shaped Shells

• The closest shellfish in both color, texture and flavor to conch are scallops, which also have a sweet taste and firm, white flesh. Small bay scallops work especially well for ceviche because they are small enough to "cook" in lime or lemon juice whole, and look like white pearls when you serve them. Cut sea scallops into strips or small chunks before marinating. Both types of scallops are sustainable choices.

Pink Gems

• Even though shrimp and lobster have a different color and flavor than conch, they are still sweet shellfish with firm flesh that hold up well to marinating. Marinate smaller-sized shrimp whole so they can keep their shape, and cut larger-sized shrimp or lobster into 1/2-inch pieces so they marinate evenly. Both lobster and shrimp vary in sustainability depending on their habitat and how they are fished or farmed.

Ceviche in a Flash

• Sole and tilapia may not have the same dense flesh as conch, but the delicate flesh of these fish gives them the advantage of cooking quickly in a marinade, and both fish are sustainably fished or farmed. In order for the marinade to effectively penetrate the flesh and cook the fish evenly, cut it into bite-sized pieces. First, slice the fillets lengthwise into 1/3-inch-wide strips, then cut the strips into 1/2-inch pieces.

Fish to Sink Your Teeth Into

• Fish with the same white, dense flesh as conch that work well for ceviche include halibut, red snapper and grouper, all of which have varieties that are and are not sustainable. As with any fish you choose for ceviche, buy the freshest pieces available from a fish market or fish department that you trust, and ask the fish seller if the particular fish is suited for ceviche.