Fish & seafood are a great source of protein. Also they contain healthy fats & omega-3 fatty acids that help keep your heart healthy. Therefore eating fish& seafood is good because of healthy benefits of it. However eating of wrong kind of fish more frequently may raise the level of mercury in your body. This is especially dangerous for pregnant and breastfeeding women because fetus and new-borns are very sensitive to mercury. Therefore it cannot be disadvantage if we know which fish to eat or which fish to avoid eating frequently.

All fish contain traceable amounts of mercury. However eating high mercury level fish more often may cause problems.

Mostly Big fish have more mercury. The simple reason is that big fish usually live longer having enough time to build up higher mercury level. In this fact, eating small fish is more better than eating big fish more often.

Below is the list of fish according to their level of mercury.
 
 
 

 Again as a way to easy remembering,small fish is with lower mercury level while larger fish contain higher mercury level.