Symptoms of a Pregnant Goldfish

Goldfish don't actually get pregnant by definition because they, in fact, lay eggs. However, there are signs that will tell you if and when your goldfish are breeding. Both males and females behave differently and show distinct physical signs. Breeding goldfish is difficult in captivity and doesn't happen by chance the majority of the time.

  1. Males and Females

    • Identifying the sex of a goldfish is not easy, but females tend to be plumper than males. Male goldfish also have tiny bumps on their face called tubercles. Ideally, goldfish intended for breeding should be two to four years old and thus sexually mature. The female should be heavy at the rear and have a soft anal area. Only females that are perfectly healthy will produce fertile eggs. Males should also be healthy and able to swim fast, as they will eventually chase the females in order to stimulate the release of her eggs. Two males are recommended per female.

    Conditions for Breeding

    • Goldfish usually won't breed successfully unless their environment and diet meets a number of conditions. The water in the tank or pond must be clean and free of all toxins. The water should be slightly cooler than normal, around 68° F. There should also be some kind of real aquatic plant life present. Females are more likely to lay eggs if they are fed live food, such as blood worms or insect larvae, instead of common fish food. Goldfish usually breed in the spring after a cold winter.

    Pre-Spawning Signs

    • Goldfish appear and behave differently when they are about to spawn. Males and females tend to group closely together when they are about to breed. The colors of the fish will also appear brighter than usual. Females will appear larger as they are ripe with eggs waiting to be fertilized. Males will behave more aggressively, and the tubercles on the face and fins are noticeable.

    Fertilization

    • Goldfish breed in the morning. You'll notice the fish behaving erratically: the males chase the females who will hang around the plants at the bottom. Eventually, the female releases her eggs, usually around 10,000 at a time. The eggs are tiny and covered in a mucous-like substance. As soon as the eggs are released, the male fertilizes them by depositing his milt. The eggs will remain in place until they hatch; though you should remove them as soon as possible. If not, the adult goldfish will eat the eggs and the babies after they hatch.

    After Fertilization

    • Goldfish eggs usually hatch about three or four days after fertilization. The vast majority of baby goldfish will not survive, even under ideal conditions. It's important to separate babies from their hungry parents right away. Spawning mops are useful for collecting and moving the eggs. Baby goldfish develop into small adult versions within four or five months, at which point they begin to display colors on their bodies. Water conditions and temperatures should be carefully monitored to help the babies' chances of survival.