Image copyright iStock Image caption The rainbow trout has been labelled as the true victim of the move

If you think there's something fishy about the salmon you're eating, that could be because it's not salmon.

New rules introduced in China mean rainbow trout can now be labelled and sold domestically as salmon.

Why? Because a media report earlier this year caused a splash by revealing that rainbow trout had for years been labelled as the similar-looking fish.

Authorities decided that instead of banning the practice, the best solution would be to legitimise it.

Rainbow trout are freshwater fish whereas salmon are born in freshwater but then live much of their lives in saltwater.

The two species are outwardly different, but inside, both have reddish meat and closely resemble each other.

They're so similar that in May, state media outlet CCTV revealed that a third of fish that had been sold as salmon in China was in fact rainbow trout from Qinghai province.

There was a furious backlash from consumers in China, particularly over fears that trout is more susceptible to parasites.

The China Aquatic Products Processing and Marketing Alliance has now announced in a ruling that to standardise the industry, salmon was now considered to be the "umbrella name of the salmonidae fish".

That's a scientific category which includes trout as well as other similar fish.

'Are crayfish now lobster?'

The ruling has got people complaining that they've been misled, but there's also a degree of sympathy for the reassigned rainbow trout.

#RainbowTroutBecomesSalmon has been trending on social media platform Weibo.

Image copyright iStock Image caption The rainbow trout fillet does look remarkably similar to a salmon fillet

"The trout must be confused. After so many years its identity has suddenly been changed to a salmon," said one person on Weibo.

Many have their own suggestions for what could be re-labelled next.

"Can we label seas and lake as the same thing? They are technically the same," said one social media user.

"Let's label the crayfish a lobster instead," another said.

"If industry standards are determined by the manufacturers, can students mark their own test scores?" one asked.

Some consumers also voiced their fears about parasites again, and whether it was safe to eat salmon raw, as is common in China.

However, according to the China Fisheries Association, domestic rainbow trout are bred in safe and quarantined conditions so there's no need to worry.

"Whether salmon has parasites does not depend on whether it is bred in sea water or fresh water," it said.