听力原文：W: I've been reading about a new healthful snack food. It's made from fish. Have you heard anything about it? M: No, I haven't, but I don't like fish very much any-way. W: Not to worry. Although it's made primarily from fish, it actually doesn't have a fishy taste. In fact, it can be flavored with tomato, cheese, or chocolate, for in-stance. M: How can it not taste fishy? Do you know how the snack food is made? W: First, the fish is minced, and cooked, and fermented. Then water and starch are added to make a dough. M: It sounds awful. Actually, the dough is very bland at that point, so the flavorings are added to give it some taste. Well, it still sounds a little strange, but I sup-pose this product will at least be low calorie and high protein like a health food. W: Yes, you could call it that. And it has alone shelf life so it won't spoil quickly, and it's also easy to digest, and can be made from types of fish that usually aren't eaten, or from high grade fish by-products, M: Hmmm. Have you got any samples? I might be willing to try the cheese flavored variety. W: No, none of it seems to be available yet. I understand it, this fish snack food probably won't be in the stores for another couple of years. So you'll have a while to get used to the whole idea. M: A couple of years, huh? It may just take me that long. But thanks for telling me about it. What is the main topic of the conversation?