Fish is allowed. Meat and meat products are not.

Fish and Mushrooms/Fungus are all allowed.

Fruits, Plants and Seeds are absolute NO NO.

http://www.cbp.gov/xp/cgov/travel/clearing_goods/agri_prod_inus.xml

I always declare on the form I have food items, AND write down what they are. They are all allowable items. Never have any problem

In my opinion, it is better to declare what you have then try to hide.