I have been fishing in battery point and around that area, in the Derwent Estuary River, I see signboard saying that you can't eat the scale fish and shellfish as the water is heavy metal contamination. Does that mean we can't eat the fish? But again on the right, it shows the fish you can take in homes and in bags.

I have attached an image of that signboard that I talk about. Just zoom in see the written content. Please, guys, any suggestion will be much appreciated.

I didn't know about that. But then again I have never been to Tasmania.

As the sign says. Don't eat any shellfish such as oysters, mussels, clams etc. Shellfish are all filter feeders which means heavy metals build up quicker and in higher amounts.

Bream eat shellfish !! So don't eat bream.

Here is a link to more info - https://www.derwentestuary.org.au/seafood-safety/

One or two meals per week is safe, but see the above link for more details.