How Long are Seahorses Pregnant?

3 min read

Seahorses are a very unique fish because of their appearance but once you get to know them, they are also very unique because of their characteristics.


Seahorses and their cousins, the pipefish and the seadragon, are the only species where the male is the one who gets pregnant and gives birth to the babies.

A question I get a lot is, how long are seahorses pregnant, many times form an accidental pregnancy in ones tank and now they are wondering how long they have to get a situation ready for the unbelievable number of seahorse babies are dancing around, waiting to be fed or being eaten by their parents – not joking but more in that later…

Seahorse males are pregnant for 2-4 weeks, depending on the species and the water temperature. This period of time is called gestation and the warmer the water is, the shorter it will last until the male seahorse ejects the newborn babies with muscular contractions in rhythm, similar to those of mammals.

It is easy to say how long seahorses are pregnant for, but there is more to it than the length of time…

Why are Seahorses Pregnant for 2-4 weeks?

BigBellySeahorse PetAquariums How Long are Seahorses Pregnant?

Seahorses are pregnant for as long as they are because there is a complex process going on inside their pouch which fully develops the seahorse babies to be self-sufficient when they are born.

Scientists discovered that the seahorse will gently sway back and forth after he receives the eggs so that they settle into his pouch, but they don’t just hang out in their loose.

The eggs are eventually covered by tissue and deeply embedded in the pouch.

Seahorse fathers give the eggs oxygen and prolactin. Prolactin is very intriguing because it is similar to milk produced by pregnant females of other species and gives nourishment to the eggs while they stay at the proper temperature.

Scientists have found that more than 3,000 separate genes are used in different processes, including the seahorse father transferring nutrients to the developing babies.

A specific example is the ability of the seahorse father to give calcium and energy-rich fats so the babies can build their unique skeletons and round bone platelets that will become part of the seahorse’s defense from predators and is also one of their unique characteristics.

Another example going on inside the pouch is the removal of carbon dioxide and nitrogen or waste from the babies.

Apparently, seahorse dads can also keep infections out of the pouch by sending antibacterial/antifungal molecules to fend off pathogens.

Male Seahorse During Pregnancy

Before becoming pregnant, the male seahorse was involved in a very interesting courtship that lasts for days.

They both would swim together in synchronized movements while wrapping themselves around each other so when the time comes to transfer the eggs, they will already be moving in perfect unison.

While the male is pregnant though, he is transferring some of his energy to the developing eggs in this pouch.

He will become much less active and maybe even lose interest in food at first.

During this time, the female still comes every day to visit him and they may try to dance around a little bit but nothing like they were before.



I hope we have shown how long seahorses are pregnant and why they are pregnant for this length of time.

If you enjoyed this article on seahorses, please check out our other seahorse articles.

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