Could anyone help me figure out how to set prices for my fish?

I saw the link that someone gave the FirstofMay, but I can't get it to open

Yeah, the new forum software broke all of the old links. We will try to fix them as we get time. Until then, all you have to do is look below the game forums, and you'll see the guide forums. The lists are contained in the Fish Tycoon Guide.

Place your fish down in the breeding area and click on your fish to look and the details and change your price there.