When a female goldfish is ready to spawn, she changes physically and behaves in a peculiar way. There are several ways to tell if your goldfish is about to spawn. First, try to understand if there are the right conditions for this to happen. Then, try to understand if the male and female goldfish perform the typical behaviors of the phase that precedes spawning. Although rare, it is possible to purchase a female goldfish that is close to spawning. Otherwise, the female will only reproduce if the male is also present.
Steps
Part 1 of 2: Check the Conditions
Step 1. Find out if your fish is female
The best way to find out the sex of your goldfish is to ask for it when you buy it or to consult a veterinarian. That said, females are usually chubby. Seen from above, females generally have a larger belly, while males are thinner. Additionally, the female pectoral fins (located just behind the gills) are shorter and rounder than those of the male.
Also, goldfish typically do not spawn until at least one year of age
Step 2. Consider the season
If you keep your fish outside, it will only spawn in the spring or early summer. If you've always kept it inside, it could lay them down at any time of the year. When determining if the goldfish you keep outside your home are going to spawn, consider what season it is.
Step 3. Check the water temperature
Goldfish are more likely to spawn in waters around 20 ° C. If you think your fish is about to spawn, check the water temperature to make sure it is optimal.
Part 2 of 2: Identifying Behaviors That Prevent Egg Laying
Step 1. Look for nuptial tubercles on male goldfish
When the male is ready for fertilization it develops small white bumps, called nuptial tubercles, on the head, gills and pectoral fins. If you notice these white dots on the male, there is a greater chance that the female will lay eggs.
The tubercles may be difficult to see. If you don't see them, that doesn't mean the female isn't reproducing
Step 2. Observe if the male chases the female
When preparing for fertilization, it is possible for the male to chase the female in some kind of dance. In many cases, this behavior is much more common than the appearance of nuptial tubercles (which can be difficult to spot).
Step 3. Pay attention to the activity level of the fish
When the female has to lay eggs, she usually starts moving more slowly. Notice if he moves slowly or seems to have difficulty moving.
You may also notice that the female prepares for nesting, or spends a lot of time hiding in secluded places or behind plants
Step 4. Notice if the fish refuses food
When she has to lay eggs, the female may refuse food. If he doesn't eat a lot, he may soon lay down.
Step 5. Notice how big the fish's body is
Female goldfish are usually somewhat rounder than males. When the female has to lay the eggs it is possible that her belly becomes even bigger and is a little protruding.
