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How Long Are Zebra Danios Pregnant For? Facts & FAQs

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By Lindsey Stanton

zebra fish denio

Zebra Danios, also known as the zebrafish, are cool animals to have in an aquarium no doubt. This fish comes from Eastern India and the areas surrounding it, making it a tropical freshwater fish that is fairly easy to take care of. Zebra Danios are fairly hardy, they can handle varying water conditions, and they don’t need that much maintenance.

They are great fish for community tanks because they tend to be pretty peaceful, a positive aspect that many fish keepers love. Also, these little fish can grow to be around 2 inches long, they don’t require a huge tank, and they can live for around 5 years if you treat them right.

One question that many people have been asking us is how long these fish are pregnant. So, how long are zebra danios pregnant?

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Zebra Danios Pregnancy

Well, this is quite an interesting question, one that does not apply to this type of fish. You see, pregnancy means carrying the fetuses and the fish fry within the body. This involves a period of gestation where the offspring develop within the body of the mother.

Are Danios Livebearers?

In other words, zebra danios are not livebearers, which means that as opposed to giving birth to live fish, they lay eggs.

The embryos develop into fish fry within the eggs and hatch from there, instead of developing within the body of the mother and being born from within the womb. With live-bearing fish, just like with human beings and mammals of all kinds, embryos, and then fetuses, are carried by the mother for a full term until they are ready to be born.

To be clear, zebra danios are not pregnant for any amount of time because they are not livebearers. They lay their eggs, they get fertilized by the male outside of the female’s body, and the fry comes to term and hatch out of those eggs.

Zebra Danio
Image Credit: bclay29, Shutterstock

Zebra Danio Breeding

Even though zebra danios lay eggs and are not livebearers, and are therefore never actually pregnant, they still go through their breeding rituals. Also, if you would like to breed these fish, there are some things that you should probably know to help make the process easier for you.

  • If you want to mate zebra danios, a really easy way to do it is to get a school of about a dozen fish. Zebra danios mate for life and they like to find their mates, so finding roughly an equal amount of males and females will ensure that at least some of them pair off and mate.
  • If you notice that your fish have paired off into clear male and female pairs, it is a good sign as mating is bound to happen. At the same time, if you notice the bellies of the females becoming enlarged and bloated, chances are that they are carrying around eggs that are ready to be scattered and fertilized. If you notice these things, it is time to set up the breeding tank.
  • You should set up a breeding tank with pretty shallow water. The water should be roughly 6 inches deep. Warmer water is ideal for spawning as it tells the fish the mating season is near. It will help to raise the water temperature to around 78 degrees Fahrenheit to encourage spawning.
  • You should get a spawning grid or some fine-leafed plants at the bottom of the breeding tank. You should also add some coarse gravel as a substrate. This is because zebra danios are known to eat their eggs and sometimes the fry once they are born. Adding these items into the breeding tank will ensure that the eggs are fairly well protected from the mouths of the adult zebra danios.
  • Once again, this will help ensure that the eggs and fry are not consumed by the parents. It will take about 2 days for the eggs to hatch into zebra danio fry, at which point you should leave them in the tank until they are almost fully grown.
  • You don’t want to put these fry back into the community tank too soon, especially until they have gotten to a decent size.
Zebrafish danio
Image Credit: topimages, Shutterstock

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Frequently Asked Questions

How Long Do Danios Live?

Your average danio is going to live for between 2 to 3 years. A well-cared-for danio may live for up to 3.5 years, but that is pushing it.

zebra danios
Image Credit: slowmotiongli, Shutterstock

How Long Do Danios Carry Their Eggs?

A pregnant danio will usually carry her eggs until she is ready to lay them. They can carry their eggs for any amount of time really, and it all depends on when they are ready to lay eggs and if there is a male around to fertilize them.

Technically speaking, if there are males around and they are developing eggs, they should not be carrying them for more than 4 days.

How Do I Know When My Danio Is Ready To Lay Eggs?

A zebra danio is ready to lay eggs when you see her midsection bulging with lots of little circular protrusions.

They will get very large and chunky. When the male starts chasing the female a lot, it also usually signifies that the female is ready to lay eggs.

Zebra danio GloFish - Danio rerio
Image Credit: boban_nz, Shutterstock

Do Zebra Danios Eat Their Eggs?

Yes, zebra danios will eat their eggs and they will eat the hatched fry as well. For this reason, once spawning is completed, you will want to remove the parent fish from the equation.

How Can You Tell If A Zebra Danio Is Male or Female?

The big difference between male and female zebra danios is their size and shape.

Males will usually have more of a torpedo-shaped body and may also be a bit shorter, whereas females tend to be a bit larger. It’s the only good way to tell at a glance.

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Final Thoughts

So in terms of the question of the day, zebra danios are not pregnant for any amount of time because they are not livebearers. They do lay eggs, but that is not at all the same thing. In terms of breeding these neat little creatures, we hope that the tips we outlined above have been of help.

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Feature Image Credit: Kazakov Maksim, Shutterstock 

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