How to Tell If a Goldfish Is Pregnant

How to Tell If a Goldfish Is Pregnant

Goldfish are a common pet for people looking for a low maintenance companion. While a normal, healthy goldfish can be quite easy to care for, they are still living, breathing animals. This means your fish can fall ill, get into fights and reproduce. Goldfish pregnancies are not necessarily anything to worry about, but they can be unexpected and you don’t want to be shocked by the sudden appearance of lots of baby fish. To help you be prepared, here is our guide about the signs to look out for in a goldfish pregnancy.

Can Goldfish Get Pregnant?

The truth is goldfish don’t actually get pregnant. They do not have the ability to carry and gestate a fetus, which they then give birth to. So why are we bothering to write this article? Well, goldfish are oviparous. They do carry and develop eggs, which they the release for fertilization, and this process is commonly known referred to as ‘pregnancy’.

Breeding your goldfish can be an easy and fun challenge if you are interested in learning more about your pet. The process is known as spawning, and you will, unsurprisingly, need to have a female and male goldfish who are sharing the same tank. The female will release her eggs, and the male will fertilize those eggs by releasing their milt. If you want these eggs to hatch and grow, you will need to separate them from their parents as goldfish frequently eat their eggs and fry.

Finding Out Your Goldfish’s Sex

It is always a good idea to ask ‘What gender is my goldfish?’when you buy the goldfish. This way you don’t have any unexpected surprises if you are trying to avoid dealing with lots of fish babies. This isn’t always easy. If you got your goldfish from a friend who didn’t know how to tell the difference, for example, you might have to figure it out for yourself.

There are three characteristics that show that your goldfish is female:

  1. A rounder, fuller belly, even when not pregnant
  2. Shorter and rounder pectoral fins, which are the fins immediately behind the gills
  3. A slightly thicker and more protruding anal vent, particularly as breeding season approaches

Unfortunately, these are all very subtle signs, and it may take some time to see them and to become experienced in noticing the signs. If it is important for you to know the sex of your goldfish for certain, you should consult your vet.

When Might Your Goldfish Get Pregnant?

The first step to understanding if your goldfish is pregnant, is to understand if it is even possible for them to be carrying eggs. It is important to point out that, unlike with mammals, the lack of a male in the tank does not make pregnancy an impossibility as your female fish may still release eggs. This does, however, make it impossible for those eggs to be fertilized, so you will not end up with any baby fish. You may not even notice your fish was ever pregnant as goldfish often eat their spawn.

The requirements for a goldfish to get pregnant include:

  • The fish must be at least one year old, and is usually larger than four inches long
  • It must be breeding season. This varies, but is naturally spring to early summer. Outdoor goldfish will breed during this time period, while indoor goldfish may spawn at any time of the year.
  • Similarly, water temperature is important and your fish will spawn when the water in their tank is 68 degrees Fahrenheit.

Pregnant Goldfish Behavior

If the conditions for pregnancy are met, it is possible that your fish is pregnant. In which case, you should look out for any physical symptoms. There are three crucial signs of goldfish pregnancy for you to look for:

  1. Changes in their size or shape

As female goldfish are generally naturally rounder, it can be difficult to tell when they are carrying eggs. However, a larger belly that sticks out should be noticeable in pregnant gold fish, particularly if they are close to laying their eggs.

  1. Changes in their activity levels

A gold fish that is preparing to lay their eggs usually slows down and may even appear sluggish. Some fish appear to ‘nest’, by hiding out in shelters and plants.

  1. Changes is feeding behavior

Pregnant goldfish also start to eat less when they are about to spawn. If you notice one of your fish refusing their goldfish food, it may be a sign that they are going to lay their eggs soon.

Male Goldfish Behavior

Keeping an eye on the female goldfish is not the only way to tell if they may be pregnant. Male goldfish also react to the upcoming spawning, so it is worthwhile to look for any symptoms that they are preparing to play their part in fertilization. The two signs of this are:

  1. Chasing females

Male goldfish that are expecting to spawn can often be seen chasing and bothering the female fish in an attempt to encourage them to lay the eggs. In particular, they may nudge the female’s bellies.

  1. Tubercles

Tubercles are small white bumps, and they can appear on a male goldfish’s head, pectoral fins and gills. They develop in expectant males, but can be very hard to see, so don’t pin all your conclusions on seeing these tiny bumps.

Breeding Your Goldfish

If you are interested in encouraging your goldfish to mate and produce offspring, there is not a lot you need to do other than ensure a male and female share a tank during breeding season. For indoor fish, this could be any time when the water is not too cold.

Caring for the spawn, however, is the crucial step as goldfish are known to eat their eggs and their fry. To care for the spawn, you should:

  • Provide a specific spawning mat, or make your own from a brand-new, unused mop head
  • Remove this breeding ground to a separate tank after spawning has occurred. Normally, this is early in the morning and takes around 3 hours.
  • Fertilized eggs are golden brown, while unfertilized eggs are white. After twelve hours check the spawning mat and remove any white, unfertilized eggs.
  • The eggs will hatch in between 46 to 54 hours, if the water temperature is 84 degrees, and between five to seven days if the temperature is 70 to 75 degrees.
  • The fry then survive off their own yolk sacs, and when these are empty you should feed them live food like brine shrimp and daphnia three times a day.


  1. How to Tell if a Goldfish Is Pregnant, Wiki How
  1. Dj
    Oct 10, 2021

    This is amazing 🤩

  2. JACQUELYN Burton
    Jun 04, 2021

    My fish shocked me .I’ve never had or ever seen any baby fish born in any tank I’ve ever had,so I’m new at this .they have 3surviving babies I’m so excited and doing well I’m feeding them the shrimps live food that’s when things changed I changed their food from flak to live food then babies was born.but the mama fish she lays to the bottom of tank all the time in same spot. What does it means?

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