question about vegetarians?!

You are not the only person to feel like this. There is actually a new category out there called FLEXITARIAN. Yes, really! Is basically means someone who is not quite committed to being a full-time vegetarian, but is reducing their intake of animal products. Some flexitarians choose just one category eg poultry/fish, in your case shrimp. Others restrict their meat-eating to certain days eg just once a week. People choose this lifestyle for different reasons eg health/eco-conscience and in this day and age it really is a sustainable and acceptable way of eating. There is even a wikipedia article about it - you can't get more "acceptable" than that!!

Many people choose to be pescitarian (eating fish, no other meat) for health reasons. Fish is very good for you as long as you consume it in moderation. It's much healthier than eating hamburgers and chicken nuggets everyday.
Plus many people just don't like certain types of meat. If you eat fish that doesn't mean you have to eat every type of meat. That's like saying just because you like cucumbers you HAVE to love every other type of vegetable.
But in the end, it's your choice whatever you eat. Your dad will eventually adjust to your decision. :)

I'm not being funny, but as long as your dad's not eating shrimp and scallops, whats he so bothered about? its your life, you can eat/do what you want with it.

like you said, its hard being a vegetarian in your family.