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upstart writes in with an IRC submission:

Scientists Accidentally Bred the Fish Version of a Liger:

American paddlefish and Russian sturgeon were not supposed to be able to create hybrid offspring. Surprise!

[...] At first glance, American paddlefish and Russian sturgeon seem about as different as two fish can be.

The Russian sturgeon, whose eggs are used to make top-shelf caviar, is a carnivore that hoovers crustaceans and smaller fish off the floor of rivers, lakes and coastal areas the world over. The American paddlefish, found in only 22 of the United States, is a filter feeder that strains zooplankton from the water. It has a comically long snout covered with tens of thousands of sensory receptors.

[...] Last year, researchers were trying to induce gynogenesis, a form of asexual production that requires the presence of sperm, but not the actual contribution of their DNA, in Russian sturgeon.

Something unexpected happened: The paddlefish sperm the researchers were using successfully fertilized the sturgeon eggs.

[...] Hundreds of hybrids emerged from those eggs and a month later, more than two-thirds of them were still alive. Around 100 of these hybrids are alive today.

Both creatures are known as “fossil fish” because of their ancient lineage. Their last common ancestor swam during the age of the dinosaurs, and the two have been evolving independently, on opposite sides of the planet, for over 184 million years — which makes them nearly twice as evolutionarily diverged as humans and mice. That led scientists to assume that they were too evolutionarily diverged to be hybridized.

Journal Reference:
Jenő Káldy, Attila Mozsár, Gyöngyvér Fazekas, et al. Hybridization of Russian Sturgeon (Acipenser gueldenstaedtii, Brandt and Ratzeberg, 1833) and American Paddlefish (Polyodon spathula, Walbaum 1792) and Evaluation of Their Progeny, Genes (DOI: 10.3390/genes11070753)

Original Submission