Which animal has the most extended period of gestation for a fish?

The animal with the longest gestation period for a fish is the elephant shark. Elephant sharks belong to a family of sharks called Callorhinchidae and are found in the waters surrounding southern Australia and New Zealand. Their gestation period lasts for approximately 22 months, which is the longest known gestation period for any known fish species.

During this time, the female elephant shark will carry her developing embryos in her uterus, receiving nutrients from a yolk sac until they are born. Unlike most fish species, which lay eggs, elephant sharks are among the few species that give birth to live young. The pups are born fully developed and equipped with their own set of teeth, ready to hunt for prey.