Fish do live in the desert!
Their real name is sand skink (Scincus mitranus ), but they are commonly known as “desert fish”. They are actually reptiles and look like lizards with tiny legs. They are rarely seen, because they will “dive” into the sand when they feel vibrations and pop up a few meters away.
They will not “swim” after you to attack you, but in case of a confrontation, they are brave little critters and will not hesitate to fight back. So if you see one, it is best to let it “swim” away.