In what Australian officials called an outrageous fraud, Japanese fishers probably used a series of disguises for the overcatch and international investigations have found.

The fishers described southern bluefin tuna as a different species and evaded any inspection on shore, underreported the amount of the fish they caught, and imported it as different tuna either transhipped at sea from foreign vessels or in containers. In a review that the Japanese government has vetoed from public release, investigators found the fraud extended to consumer markets.

A study published in Nature demonstrates that fish have a natural rhythm that could help them avoid being eaten by predators

A team from the University of California led by Dr Mu-Ming Poo made the discovery during experiments with zebrafish, a type of minnow. They discovered that the larvae of the fish, which were trained to flip their tails every time a light flashed at six-second intervals, "remembered" the rhythm even after the flash was turned off.

The reason why the fish kept time was a mystery but it could be to help it keep track of time and defend itself.

The mangrove rivulus, also known as the mangrove killifish, is native to the Americas and is about five centimetres (two inches) long.

The fish has long been studied for its many unique features. It's the only vertebrate known to naturally self-fertilize, for example. In some populations, it can become a hermaphrodite, developing both male and female parts simultaneously, to produce clones of itself.

Costa Rica hosts an active industry for collection activities on marine ornamental reef fish for the international aquarium fish trade. Little is known about the effects of collection activities on target species in Costa Rica. However, research elsewhere gives reason for concern about collecting activity rainbow wrasse (Thalassoma lucasanum) is an important species in this fishery.

In the case of cod in the North Sea, eastern channel and Skagerrak...things took a turn for the worse in 2008, when a greater proportion of the stock was caught than in any year since 1999," the European Commission said in a statement.

"We are not that far away from a situation of complete collapse," said Jose Rodriguez, a marine biologist with the environmental group Oceana.

Conservation measures for desperately depleted cod have not delivered the promised revival of supplies – partly because of continued over-fishing exceeding agreed quota limits.

According to an analysis of the Atlantic cod’s genome, scientists have discovered the fish have evolved to survive without a set of genes thought essential to the immune system. It is hoped the finding will lead to better vaccines for farmed cod and even open new avenues of medical research for human disease.

The unique fish is called the Benguela-goby, or bearded goby, and is found only on the anoxic continental shelf outside Namibia and South-Africa. Since the collapse of the sardine fisheries, this goby has become the new predominant prey species for larger fish, birds and mammals in the region

The Ocean Research & Conservation Association (ORCA) and its collaborators announced today the world’s first use of an acoustic underwater camera to survey juveniles of goliath grouper in mangrove habitats.

"In nearly 500 million years of vertebrate evolution, and many thousands of vertebrate species living and dead, this is the only one known to have solved the fundamental optical problem faced by all eyes - how to make an image - using a mirror," said Professor Julian Partridge, of Bristol University.