KidSafe Seafood lists species by contaminant level, sustainability or omega-3 level. You can also look up species by name.

Low Contaminants: Safe to eat four or more times per month
High Contaminants: Safe to eat three or fewer times per month

High Omega-3s: Eating three or fewer meals per week will reach the recommended intake

Best Choice: the species is one of KidSafe Seafood’s Best Choice species

Ocean-Friendly: Sustainably harvested
Somewhat Ocean-Friendly: Somewhat sustainably harvested
Not Ocean-Friendly: Not Sustainably harvested

0-6 year old: 3 oz serving size per meal
6-12 years old: 4.5 oz serving size per meal
A standard deck of cards is roughly 3 oz