At what age is it a healthy idea to introduce fish and shrimp to a child?

Sooner the better! As long as there is no reason to think your child has food allergies to the items in question, just try it! There is some evidence that introducing foods like fish before 9 months is beneficial to the immune system and future tolerance of the food. As long as the food is soft (no choke hazards) and not honey (botulism risk), infants >6mo can try what you eat!