These fish has more high level of mercury they are:
Shark
Ray
Swordfish
Barramundi
Gemfish
Orange roughy
Ling
Southern blue fin tuna.Fish with lower mercury are:
Shellfish including prawns, lobsters and oysters
Salmon
Canned tuna.
the european union agreed on monday the 11th to restrict the fishing of the blue fin tuna in the eastern atlantic and meditaranean in the hope of reviving dwindling tuna fish stock,
i think its a step in the right direction