http://www.snopes.com/fukushima-radiation-marine-photos/ And:...

http://www.snopes.com/fukushima-radiation-marine-photos/

And:

http://www.snopes.com/photos/technology/fukushima.asp

All false. Fish on the Great Barrier Reef are NOT radioactive. Tumours on sharks are not caused by radiation from Fukushima - the photo was taken in 2004. Etc, etc etc.  It's all part of a scaremongering campaign spread by people who either have hidden anti-nuclear agendas, or who are ignorant of the facts and don't bother to check.