How To Tell if a Goldfish Is Pregnant – Our Helpful Guide

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Goldfish have been popular pets for families and kids for decades, and they can live for as long as 30 years if given optimum care.

These gorgeous fish will breed if given the right conditions, especially if you keep your goldfish in a large group in an outdoor pond. So, how do you know if your goldfish is pregnant?

Well, a pregnant female goldfish will be quite plump, and you might even see a few eggs falling from her if she bumps into things in the tank.

But how old must goldfish be before they can get pregnant? And do adult goldfish eat their eggs and fry?

Keep reading to learn more about goldfish pregnancy.

Do Goldfish Lay Eggs?

can goldfish live alone

Some fish species lay eggs, while others give birth to live young.

Goldfish are egg-layers. The female goldfish carries the eggs inside her body before depositing them on plants or flat stones, where the male fish fertilizes them.

Is My Goldfish Male Or Female?

Obviously, you can’t breed from your goldfish unless she’s female and you have a male to mate with her.

So, how do you tell if your goldfish is male or female?

There are several features to look for that will give you a good idea of the sex of your goldfish, including the following:

  • During the spawning season, male goldfish have white breeding tubercles or spots on their gill covers.
  • Female goldfish have a vent that sticks out.
  • Male goldfish chase females around the tank as a prelude to spawning.
  • Male goldfish tend to have thicker, more pointed pectoral fins than females.
  • The anal fin is closer to the tail in male goldfish than in females.
  • Male goldfish often have more flowing tails and fins than females, although that depends on the variety.
  • Male goldfish are usually somewhat smaller and more slender-bodied than females.
  • When pregnant, the female’s body is asymmetrical when viewed from above because of the burden of eggs.
  • The ridge running through the rear of the pelvic fins to the ventral opening is typically more pronounced in males and absent or smaller in females.

Unfortunately, if you keep round-bodied Fancy goldfish rather than slender-bodied varieties, it can be very difficult to tell the difference between the two sexes.

The goldfish you buy from your local pet store are juveniles, so it’s almost impossible to differentiate between the sexes. So, if you want to breed from your fish, the best ploy is to buy a small group of five or six individuals. That way, you can be pretty sure you’ll end up with a mix of the two sexes.

When Are Goldfish Sexually Mature?

Although most goldfish varieties are not fully grown until they are two or three years of age, the fish are usually sexually mature when they are around one year old.

How Do I Know When My Goldfish Is Pregnant?

Here are a few things to look out for that might indicate your goldfish is pregnant.

Swollen Belly

The female fish’s swollen belly is the most obvious sign of pregnancy in goldfish. That’s because she’s carrying eggs inside her body. So, if one of your fish suddenly appears to have grown massively and is beginning to look fat, that’s a pretty good indicator that she’s pregnant rather than just greedy!

That said, round-bodied goldfish tend to look fat anyway, so it can be difficult to tell if they are pregnant or not!

Goldfish Dropsy or Pregnant?

Dropsy is a serious fish disease that can affect goldfish. Dropsy causes abdominal swelling, making it appear as though the fish is pregnant. However, other symptoms of this disease are very different from pregnancy, including:

  • Bulging, swollen eyes
  • Scales begin to stick outward instead of laying flat against the fish’s body, giving a pinecone-like appearance.
  • Faded gill color
  • Clamped fins
  • Curvature of the spine
  • Pale feces
  • Anal swelling

In addition, the fish will stop eating and will appear very lethargic.

Frayed Fins

Pregnant goldfish often suffer from frayed, ragged fins. That’s largely caused by the male’s pursuit and nipping as he tries to fertilize the eggs during courtship and can also be the result of stress.

That said, frayed fins can also be caused by bacterial infection, so it’s important to watch out for any other signs of disease that could be affecting your fish.

If you can see that the female is being relentlessly chased and harassed by the males, you might want to move her to a separate tank for her own protection and to reduce stress.

Eggs Fall Out of the Female Goldfish!

Although it seems strange, one of the crucial signs that your female goldfish is pregnant is when you notice a few eggs falling out of her. That can happen when the female bumps into objects in the tank or if she brushes against your hand during routine tank maintenance.

Once that happens, you know that the female is ready to lay her eggs imminently! If you spot a few eggs falling from your female goldfish, I recommend removing her from your main tank and putting her in a dedicated spawning tank to prevent other fish and tank residents from eating the eggs.

Some female goldfish hold onto their eggs until a male fertilizes them. However, eggs falling from a female is a reliable indicator that she’s definitely pregnant and is ready to lay her eggs.

How Many Eggs Do Goldfish Lay?

Goldfish generally lay from 500 to 1,000 eggs per spawn, although 2,000 eggs in one spawn isn’t unheard of.

After the eggs are laid, the female goldfish releases a sticky mucus that helps to protect the eggs and encourages them to stick to spawning mops, plants, or flat rocks. The male goldfish then fertilizes the eggs by releasing sperm or milt over them.

How Long Are Goldfish Pregnant Before Laying Eggs?

How To Tell if a Goldfish Is Pregnant

Since goldfish don’t bear live young, they’re never technically pregnant. However, once the eggs are laid and fertilized, they hatch in around two to seven days.

Note that neither parent fish takes any further part in raising their young. For that reason, you need to remove the adult fish from the tank once the eggs are laid, as the fish will eat them if given a chance.

Is My Male Goldfish Ready to Mate?

Male goldfish are ready to breed when they develop white tubercles on their gill covers. The appearance of these white spots tells you that the fish is ready to breed.

To confuse matters somewhat, female goldfish also develop white spots on their gill covers ready they are ready to lay their eggs. However, those spots are larger and more obvious than male tubercles.

When Is Goldfish Breeding Season?

Just like their distant relatives, Prussian carp, goldfish usually breed in outdoor ponds during the spring and summer months when the water warms up. However, goldfish will breed pretty much all year round in warmer climates.

How to Care for a Pregnant Goldfish

Once you know you have a pregnant goldfish in your tank, you must do several things to ensure the survival of the female and her fry.

Spawning Tank

Adult fish and invertebrates view fish eggs and fry as a food source, so to keep the goldfish eggs safe, you’ll need to set up a separate spawning tank.

Maintain Correct Water Parameters

Maintaining the correct water parameters throughout the pregnancy and fry-rearing process is crucial. That means the water’s ammonia and nitrite levels must be zero, while nitrates must be as low as possible and certainly not above 20 ppm.

Weekly water changes of around 50% are essential, and you must vacuum the substrate to remove fish waste and uneaten food. A sponge filter that won’t suck up the fry is also a sensible choice.

Goldfish are coldwater fish, although they typically spawn when the water is warmer. If the water temperature is too low, the goldfish eggs might not hatch, and any fry born probably won’t survive. So, if you maintain a water temperature of between 74o and 78o F, that’s perfect for the goldfish.

Tank Decoration

Goldfish fry is tiny and vulnerable for the first few weeks of their lives, so you must provide plenty of hiding places in the form of dense planting, caves, twisted roots, and the like.

High-Protein Diet

Pregnant fish need a high-protein diet for the healthy growth and development of their eggs and fry. While she’s carrying hundreds of eggs, the female goldfish uses lots of nutrients and energy, and a high-protein diet ensures she has everything she needs to produce healthy, well-developed fry.

Feed your female goldfish live foods from a reliable source, such as daphnia, bloodworms, and brine shrimp, as well as high-protein goldfish food designed and formulated for pregnant goldfish.

Ideal Environmental Conditions

An ideal spawning environment is essential for your female goldfish to keep her eggs safe and raise healthy, well-developed fry.

When the fry hatch, the goldfish babies are highly vulnerable to predators. So, keep the spawning tank free from threats, including crabs, snails, other fish, and shrimp. The perfect environment for raising fry is an outdoor pond, although you can do just as well with an indoor tank, provided it’s set up correctly.

Feeding The Fry

Once the fry is born, you can offer your baby fish brine shrimp and commercially prepared fry food.

When the juvenile goldfish are large enough, you can feed them on finely crushed goldfish flake food until they’re big enough to cope with an adult diet.

Final Thoughts

Did you enjoy our guide explaining how to tell if your goldfish is pregnant? If you did, please take a moment to share the article with other goldfish fans!

If one of your goldfish is much rounder in shape than the others and appears asymmetrical from above, it’s likely she’s pregnant. Sometimes, you’ll see eggs falling from the fish if she bumps into objects in the tank, too.

Did you successfully breed your goldfish? What variety are your fish? Tell us about your goldfish breeding journey in the comments box below!

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