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MCMCTree suggested that H. comes diverged from the common ancestor of stickleback, Nile tilapia, platyfish, fugu, and medaka approximately 103.8 Mya, which corresponds to the Cretaceous period.

They breed a swordtail and a platyfish, both common pets, to create offspring that are more sensitive to UV light.

Platyfish have a so-called tumor gene and a regulator to control it, whereas swordtails have neither.

To make sure that their baby platyfish got a germ-free start, the researchers bathed the mother fish in alcohol, ether and iodine, made a Caesarean incision and gently sucked the young out of the germless oviduct with a rubber bulb, taking care not to rupture the germ-packed intestines.

The platyfish, not an egg-layer, bears live young.