How to know when a goldfish is pregnant

Written by parul gupta
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How to know when a goldfish is pregnant
The female goldfish lays eggs that are then fertilised by a male. (Goldfish image by Lucy Cherniak from

Goldfish are popular pets, much loved by both children and adults. They liven up a fish bowl with their bright scarlet scales, and it isn't difficult to spend a couple of hours simply watching them play around in the water. Goldfish enthusiasts spend considerable time observing and studying these fish and are familiar with their body changes, behaviour, eating and breeding habits. On the other hand, if you have never had goldfish before, this can all be quite confusing. Goldfish do not get pregnant in the way we understand the term 'pregnancy'. Instead, the female goldfish lays eggs which are then fertilised by the male goldfish. It is possible to learn, however, whether a female goldfish is ready to lay eggs or not.

Skill level:

Things you need

  • Contact number and address of the pet shop where you purchased the fish
  • Contact number and address of a vet
  • Thermometer

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  1. 1

    Confirm what time of the year where you live. Goldfish breed in the springtime, and if your goldfish appears 'pregnant' in another season, it is very possible that this appearance is a result of some other factor.

  2. 2

    Determine the sex of the goldfish. Only female goldfish lay eggs and before you conclude that your fish is indeed ready to spawn, confirm that it is indeed female. 'Pregnant' female goldfish have deeper or plumper bodies than males, because they are filled with eggs. They also have a protruding vent just below the anal fin. In addition, their bellies are softer than a male's, and they have shorter and more rounded pectoral fins. If you think your fish has these characteristics, look for another fish in the bowl or tank that has white pimples or tubercles on its gills and on the edge of its pectoral fins. This is a male goldfish ready to breed, and if you find him as well, it is possible your fish may indeed be carrying eggs. If your tank is dark, use a torch to observe the fish.

  3. 3

    Find out how old the goldfish is. Goldfish are ready to breed when they turn one or two years of age. Ask the petshop where you purchased the fish how old it is or take it to a vet. Remember that not all vets are familiar with fish, so confirm this with him over the telephone first before visiting. If your fish is less than a year old, it is unlikely she is carrying eggs.

  4. 4

    Check the condition of the water in your fish bowl or tank. Goldfish can only breed in water that is absolutely clean and clear. It is also essential that it be cool---usually around 16 degrees Celsius (15.6 degrees Celsius). Use a thermometer to determine the temperature. Moreover, it is important to have real aquatic plants in the tank and no sand or gravel. Goldfish that have been fed on live food such as blood worms tend to breed more than those on a fish food diet. Match these breeding criteria with the condition of your tank to determine the chances that your fish have been breeding.

  5. 5

    Wait for a few days. If you still think your goldfish is ready to lay eggs, observe it for a few days. Spawning usually takes place in the morning. Notice if the colours of the fish have become brighter, and if a male goldfish is aggressively chasing your "pregnant" female goldfish. If she is going to lay eggs, the male will begin to push against her until the eggs are released. The goldfish lays several thousand eggs together, and you can identify these by their round and almost transparent appearance. If spawning has occurred once, it is likely it will be repeated again after a few days.

Tips and warnings

  • There are several reasons why a goldfish could appear bloated, apart from the fact that it is ready to lay eggs. Overfeeding and sickness are two such reasons. It is important to confirm with a vet or with a professional at your petshop which of these reasons apply to your fish.
  • If your goldfish is indeed ready to lay eggs, ensure that you have another tank handy to transfer the other fish to it as soon as the eggs have been laid. Separate the goldfish from the eggs, because goldfish tend to eat their own eggs. Allow the eggs to hatch on their own. Raise the temperature of the water to about 18 to 21 degrees Celsius.
  • Do not poke or prod your goldfish to determine their sex or to check if they are ready to lay eggs.
  • Do not overfeed your goldfish.
  • Maintain healthy living conditions for your fish. Keep the tank clean and free of toxins. Fill it with live plants and monitor the temperature and condition of the water.

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