Also as a general rule, fish dont really sell for much, the only exceptions i can think of now are the fish used in alchemy potions (oily blackmouth, firefine snapper, stonescale eel).
Players are tight when it comes to cooked food items from other players, they do not realise the time and effort as well as the other ingrediants involved in making that nice stack of stamina/spirit/agility etc etc giving food.
The fish that make money are as follows (from my server anyway) Stonescales Oilys Firefins Nightfin