Many goldfish keepers, especially those new to the hobby, wonder if their fish are pregnant. Unlike mammals, goldfish don’t carry their young internally. Instead, they are egg-scatterers, meaning the female releases eggs that are then fertilized externally by the male. So, technically, a goldfish isn’t ‘pregnant’ in the mammalian sense. A more accurate term would be ‘egg-bound’ or carrying eggs. This comprehensive guide will walk you through the signs that indicate your female goldfish is carrying eggs and ready to spawn.
Understanding Goldfish Reproduction
Before diving into the signs, it’s important to understand the basics of goldfish reproduction. Goldfish typically spawn when conditions are right, usually in the spring or early summer when water temperatures begin to rise. This triggers their natural breeding instincts. The spawning process involves the female releasing eggs, which the male then fertilizes by releasing milt (sperm) into the water. The fertilized eggs then stick to plants, decorations, or the sides of the tank until they hatch.
Identifying Male and Female Goldfish
The first step in determining if your goldfish is carrying eggs is to identify the sex of your fish. This can be tricky, especially when they are young. However, there are several key differences to look for:
- Breeding Tubercles: During the breeding season, male goldfish develop small, white bumps called breeding tubercles on their operculum (gill covers) and sometimes on their pectoral fins. These are the most reliable indicator of a male. Females do not develop these tubercles.
- Body Shape: Females often have a rounder, plumper body shape, especially when they are carrying eggs. Males tend to be more streamlined. This difference can be subtle and is more noticeable when the fish are mature and in breeding condition.
- Vent Shape: The vent (anal opening) of a female goldfish is typically rounder and more protruding than that of a male. The male’s vent is usually more oval and concave. This can be difficult to see without close examination.
- Chasing Behavior: During spawning season, male goldfish will relentlessly chase females around the tank. This is part of the courtship ritual.
Signs Your Goldfish Is Carrying Eggs
Once you’ve identified a potential female, look for these signs that indicate she’s carrying eggs:
- Swollen Abdomen: This is the most obvious sign. A female carrying eggs will have a noticeably swollen or rounded abdomen. The swelling will be more pronounced on one side than the other as the eggs develop unevenly. This is especially noticeable when viewed from above. It’s important to differentiate this swelling from bloating caused by overfeeding or other health issues. If the fish appears generally unwell, lethargic, or has other symptoms like pinecone scales (scales sticking out), it’s more likely a health problem than eggs.
- Visible Eggs Through the Skin: In some cases, especially with lighter-colored goldfish, you may be able to see the eggs through the skin of the abdomen. They will appear as small, yellowish or whitish dots. This is a strong indication that the fish is carrying eggs.
- Changes in Behavior: A female carrying eggs may exhibit changes in behavior. She might become more lethargic or less active than usual. She may also spend more time near the bottom of the tank. Some females may also become more reclusive, hiding more often than usual. These behavioral changes are often subtle and can be easily missed.
- Increased Interest from Males: As the female gets closer to spawning, male goldfish will show increased interest in her. They will relentlessly chase her around the tank, nudging her abdomen with their noses. This chasing behavior is a sign that the male is trying to encourage the female to release her eggs. If you observe this behavior, it’s a strong indication that spawning is imminent.
- Restlessness and ‘Shimmying’: Just before spawning, the female may become restless and exhibit a ‘shimmying’ behavior. This involves shaking or vibrating her body as she tries to release the eggs. She may also rub her abdomen against objects in the tank in an attempt to dislodge the eggs.
Distinguishing Pregnancy from Dropsy and Other Illnesses
It’s crucial to distinguish the signs of a goldfish carrying eggs from symptoms of diseases like dropsy or other illnesses. Dropsy, for example, causes the fish to swell up, but it’s accompanied by other symptoms like:
- Pinecone Scales: The scales stick out, giving the fish a pinecone-like appearance. This is the most distinctive symptom of dropsy.
- Lethargy: The fish will be very lethargic and inactive.
- Loss of Appetite: The fish will refuse to eat.
- Bulging Eyes: The eyes may bulge out of their sockets.
If your goldfish exhibits these symptoms along with swelling, it’s more likely to be dropsy or another illness and requires immediate treatment.
Other conditions that can cause swelling include:
- Overfeeding: Overfeeding can cause the fish to become bloated, but the swelling will be more general and not as pronounced on one side. Reducing the amount of food and ensuring a balanced diet can resolve this.
- Constipation: Constipation can also cause bloating. Feeding the fish some blanched, peeled peas can help relieve constipation.
- Tumors: In rare cases, swelling can be caused by tumors. These are usually slow-growing and may not be accompanied by other symptoms initially.
What to Do If Your Goldfish Is Carrying Eggs
If you’ve determined that your goldfish is likely carrying eggs, here’s what you should do:
- Prepare a Spawning Tank: To increase the chances of the eggs hatching and the fry (baby goldfish) surviving, it’s best to move the female to a separate spawning tank. This tank should be clean and cycled, with a temperature similar to the main tank (around 68-74°F or 20-23°C).
- Add Spawning Media: Provide spawning media for the eggs to attach to. This can be fine-leaved plants like Java moss, spawning mops (artificial plants made of yarn), or even plastic mesh. The spawning media should be thoroughly cleaned before being placed in the tank.
- Introduce the Female and Male (Optional): If you want to ensure fertilization, you can add one or two male goldfish to the spawning tank along with the female. Make sure the males are healthy and ready to breed. If you don’t add males, the female may still release the eggs, but they won’t be fertilized.
- Monitor the Fish: Keep a close eye on the fish in the spawning tank. Once the female has released her eggs, and the male(s) have fertilized them (if present), it’s important to remove the adult fish from the spawning tank to prevent them from eating the eggs. Goldfish are notorious for eating their own eggs.
- Maintain Water Quality: Keep the water clean and well-oxygenated in the spawning tank. Perform regular water changes (about 25% every other day) to remove waste and maintain good water quality. Use a sponge filter to avoid sucking up the fry.
- Incubation and Hatching: The eggs will typically hatch in 2-7 days, depending on the water temperature. Higher temperatures will speed up the hatching process.
- Feeding the Fry: Once the fry hatch, they will initially feed off their yolk sacs. After a few days, you will need to start feeding them infusoria or liquid fry food specifically designed for baby fish. As they grow, you can gradually introduce them to baby brine shrimp and finely crushed flakes.
Preventing Unwanted Spawning
If you don’t want your goldfish to spawn, there are several things you can do:
- Keep Only One Sex: The most effective way to prevent spawning is to keep only male or only female goldfish. This eliminates the possibility of fertilization.
- Maintain Stable Water Temperatures: Goldfish are more likely to spawn when water temperatures fluctuate. Keeping the temperature stable can help prevent spawning.
- Avoid Overfeeding: Overfeeding can stimulate breeding behavior. Feed your goldfish a balanced diet in appropriate amounts.
- Separate Males and Females: If you have both male and female goldfish, you can separate them into different tanks to prevent spawning.
Common Mistakes to Avoid
Here are some common mistakes that goldfish keepers make when dealing with spawning:
- Misdiagnosing Illness as Pregnancy: As mentioned earlier, it’s important to distinguish between the signs of a female carrying eggs and symptoms of illness like dropsy.
- Leaving Adult Fish in the Spawning Tank: Adult goldfish will eat their own eggs, so it’s crucial to remove them after spawning.
- Poor Water Quality: Poor water quality can prevent the eggs from hatching and harm the fry. Maintain good water quality in both the main tank and the spawning tank.
- Overfeeding the Fry: Overfeeding the fry can pollute the water and lead to health problems. Feed them small amounts of food several times a day.
- Ignoring Water Changes: Regular water changes are essential for maintaining good water quality and preventing the buildup of harmful substances in the tank.
Conclusion
Determining if your goldfish is carrying eggs involves observing physical and behavioral changes. By understanding the signs and taking appropriate action, you can successfully breed goldfish and raise healthy fry. Remember to differentiate between pregnancy and illnesses such as dropsy, and always prioritize maintaining optimal water conditions for your fish. Whether you’re a seasoned aquarist or a beginner, understanding the nuances of goldfish reproduction can be a rewarding experience, allowing you to appreciate the fascinating life cycle of these popular pets.