Besides the joy of owning fish, just watching your fish is enjoyable! Research shows that it can calm you and reduce stress.1 Fish also make excellent first pets for children. They are relatively easy to take care of and tolerant of less-than-ideal conditions (depending on the species), which partly explains why people buy more than 480 million fish every year.2 Breeding them makes it an even more fun—and educational—hobby.
Even though people have raised them for hundreds of years, goldfish still follow ancient patterns of breeding and laying eggs. That makes it simpler for you to take goldfish ownership to the next level. The key is having a stable and healthy environment while providing optimal nutrition.
Let’s suppose that you’ve adequately done your part. How do you know if it’s been successful? There are several indicators that can answer the question of whether your goldfish is pregnant. The right conditions are imperative, but it doesn’t end once breeding happens. This guide will cover the situation before, during, and afterward.
How to Tell If Your Goldfish Is Pregnant
Pregnancy is often defined as the development of an organism within a uterus, so strictly speaking, female goldfish don’t experience pregnancy because they lack a uterus. Goldfish lay eggs, and they undergo a spawning cycle where they lay their eggs if the conditions are appropriate. Male goldfish then fertilize the dispersed eggs externally. In other words, goldfish don’t engage in “the deed” to produce offspring, nor do they experience a pregnancy.
Let’s explore all this further!
Goldfish Reproduction
It’s helpful to know how goldfish reproduce to determine if the conditions are right and whether your pet is “pregnant.” Goldfish reproduce by laying eggs, unlike many tropical fish, such as guppies or swordtails, which give birth to live young. This makes sense from an evolutionary perspective. Goldfish, like others in their family, are prey species and opportunistic feeders. Laying eggs while evading predators and finding food gives these fish the edge they need to survive another day.
Goldfish eggs have a sticky film on them, which provides an ideal surface for attaching to plants that can provide the necessary cover. The leaves will provide camouflage and protection. However, it’s not just predators and environmental conditions that will affect the eggs. Goldfish, even the mother, may eat them. Surviving viable eggs will hatch within 4–7 days; eggs that do not hatch 8 days after being laid are considered non-viable.
At that point, the fry (baby goldfish) are on their own in their aquatic world. Providing live or artificial plants is an excellent way to give them a good chance at life. Growth proceeds rapidly out of necessity, as it’s an effective survival strategy versus live young that are well on their way on their development path. Goldfish reach sexual maturity when they’re about 1 year old.
Right Conditions
The next thing that you need to consider is whether the conditions are suitable for breeding. For example, do you have a male and a female in your tank? Do you know how to tell the difference? The first things to look for are little white nubs on the pectoral fins of your male goldfish during the breeding season, called breeding tubercles. Their precise purpose is uncertain, but it could be a defense adaptation against competing males. They should not be confused with ich (pronounced itch or ick), a parasitic infection.
Another telltale sign is the shape of the vent. This structure is located on the underside of the fish near the anal fin. Males have a more flat or concave vent with an oblong shape, while females have a round and convex vent. It will protrude when the conditions are right for egg laying.
The tank’s conditions must also be conducive to breeding. Mating usually occurs after the temperature drops and then rises, indicating the seasonal change from winter to spring. Without this indicator, your goldfish’s biological clock might not register that it’s time to breed. Many hobbyists create this environment artificially in a separate tank to speed up the process.
You can probably safely assume that your goldfish isn’t “pregnant” if you haven’t taken these measures.
Female’s Appearance
The female goldfish typically looks rounder than the male during the spawning season, making body shape an indicator of sex and the possibility of “pregnancy.” If her abdomen continues to get larger, the chances are that she’s carrying eggs and will soon be ready to spawn. The extra weight may (anecdotally) also affect her behavior. She may seem lethargic and move slower than normal.
Telltale Signs of Egg-Laying Behavior
An unmistakable sign of a “pregnant” goldfish is the presence of eggs. If you’re hand-breeding your fish, you’ll likely spur their release if you handle your female fish. You may see her hanging around the plants in your aquarium for a place to spawn. Once you see the eggs, it’s time to move your goldfish back to her regular tank. Otherwise, she may eat them. It may seem hard to understand why a female would eat her own eggs. We have to circle back to the survival instinct, as goldfish are opportunistic feeders. The fertilization of the eggs happens externally, so you need a male in the tank to fertilize the eggs.
The process of watching the goldfish fry develop and grow is a valuable learning lesson that you and your children will enjoy.
Conclusion
Breeding goldfish isn’t difficult if the conditions are right. Knowing when the female is “pregnant” will help you ensure that her young will survive. The physical appearance and behavior of the fish will provide reliable indicators that breeding was successful. The next steps are keeping the young safe and providing them with sufficient nutrition to reproduce the next generation of goldfish.
If you're new to the world of goldfish keeping or are experienced but love to learn more, we highly recommend you check out the best-selling book, The Truth About Goldfish, on Amazon.
From diagnosing illnesses and providing correct treatments to proper nutrition, tank maintenance and water quality advice, this book will help you to ensure your goldfish are happy and to be the best goldfish keeper you can be.
Featured Image Credit: Pixabay
