Here is a good thing to consider when eating fish and getting confused....

Fish that eats other fish has mercury in it, the big fish have mercury in it. Easy peasy. That is shark (Flake) orange ruffy, Marlin, swordfish, catfish, barramundi.

In the case of tuna: BLUEFIN tuna is the tuna to limit intake. Yellow fin tuna is better, which is what is in most tinned tuna.

I would assume Fish Fingers are made from Hake - the same stuff in oven fish and fillet of fish from maccas.

For more info here look here: Pregnant woman can have more then 1 serve a week granted it is low mercury fish!!

Mercury in fish - Better Health Channel.