I introduced shell fish (shrimp and crab) pretty early... maybe 13 months? Around when she first started really eating food. She loves shrimp. We eat shell fish about once a week. I grew up in Louisiana and we still live in the Gulf area. It's wild caught Gulf shrimp and crab meat. I haven't given her any meats besides wild caught fish.
I never thought twice about giving it to her. However, one of my friends said that our ped (same one) gave her a really hard time about giving her 15 month old DD shellfish and nuts. He told her he guessed the nuts were ok, but that she absolutely shouldn't be getting shellfish
. I've given DD some nuts too (cooked into breads). She's never reacted to a food. Maybe I'm careless and lucky.