A pescetarian diet is a "semi-vegetarian diet" (also called "demi-vegetarian diet"; not to be confused with a vegetarian diet). People who eat this way, eat a vegetarian diet for the most part, but will occasionally eat seafood.
Pescetarians typically eat a Lacto-Ovo vegetarian diet for most of the time, which includes dairy and eggs. I suggest finding a vegetarian food pyramid online and buy some vegetarian cookbooks. That way, you can plan healthy, balanced meals around the food pyramid.
In addition to dairy, eggs and seafood, other good sources of protein are quinoa, amaranth, hemp seeds, mushrooms, edamme, spirulina, etc.. These are complete proteins, just like meat.
Other excellent sources or protein are grains, legumes, rice, nuts, seeds, tempeh, tofu, seitan, cereal, pasta, bread, corn, broccoli, soy milk, rice milk, almond milk, hemp milk, etc..
Eat a lot of grains, vegetables, legumes and fresh fruits. There are literally thousands and thousands of different dishes you can eat. Asian and Indian dishes are two types (to name a few) of cuisines that can be made to accommodate your diet. You are only limited by your imagination.
Here is a good website to help you get started.