Breeding goldfish may seem complicated, but once you understand the key steps, even beginners can enjoy the excitement of raising baby fish! Below is a clear, step-by-step guide to help you successfully breed goldfish.
1. Preparation Before Breeding
1.1 Confirm the Breeding Season
The best breeding season for goldfish is spring, when the water temperature is between 18–25°C (64–77°F). At this time, goldfish are active and their reproductive organs are mature. In northern regions, breeding may extend into early summer, while in southern areas it is best to avoid the rainy season.
1.2 Select Healthy Parent Fish
Female: Round, swollen belly (soft to the touch near the vent) and slower swimming.
Male: White breeding tubercles (“stars”) on the gill covers and pectoral fins, with a slimmer body shape.
Recommended ratio: 1 female to 2–3 males, ideally 1–3 years old.
1.3 Set Up the Breeding Tank
Use a shallow tank at least 50 cm long, with water depth of 15–20 cm.
Keep water temperature stable at around 20°C (68°F). Dechlorinate tap water by exposing it to air for 3 days.
Place spawning mops, java moss, or palm fibers as egg-laying sites, spaced about 2 cm apart to mimic aquatic plants.
2. Triggering Spawning Behavior
2.1 Spawning Stimulus Techniques
Replace with slightly warmer water (about 2°C higher than the tank).
Extend light exposure to 14 hours per day (use LED lights if needed).
Feed high-protein live food such as bloodworms or daphnia twice daily.
2.2 Courtship Behavior
Males will chase and nudge the female’s abdomen, a behavior called “tail chasing.” During this stage, reduce feeding to avoid water quality issues.
3. Egg Laying and Collection
3.1 Spawning Process
Spawning usually peaks between early morning and sunrise.
A female releases 300–500 tiny transparent eggs (about 1 mm in diameter).
Males fertilize the eggs within 30 seconds.
3.2 Collecting Eggs
Within 2 hours, transfer the spawning mop or plant material with eggs into a separate hatching tank.
Remove unfertilized eggs (white and cloudy) with a dropper.
Change 50% of the water in the breeding tank to maintain quality.
4. Goldfish Egg Hatching
4.1 Hatching Conditions
Keep water at a stable 22°C (72°F) with no more than ±1°C fluctuation.
Provide low light and avoid direct sunlight.
Add a small amount of methylene blue (0.1%) daily to prevent fungus.
4.2 Hatching Time
At 22°C: Eggs hatch in about 5 days.
At 24°C: Eggs hatch in 3–4 days.
Newly hatched fry are transparent and survive on yolk sacs for the first 3 days.
5. Raising Goldfish Fry
5.1 First Feeding
Day 4: Feed infusoria or boiled egg yolk water (strained through cloth).
Day 7: Transition to newly hatched brine shrimp.
Feed small amounts frequently—4 to 6 times daily.
5.2 Water Quality Management
Use a sponge filter for gentle filtration. Do not change water during the first 2 weeks.
Keep water depth at 15 cm and temperature stable.
After 30 days, start partial water changes (about 20% each time).
5.3 Selecting and Sorting Fry
At 20 days: Remove fry with deformities such as bent spines or single tails.
At 60 days: Sort by color and body shape.
Common Questions
Q: Should parent fish be separated after spawning?
A: Yes, immediately. Adult goldfish will eat the eggs. Males also need rest after the exhausting process.
Q: What if I don’t have spawning mops?
A: You can tie yarn to a wooden frame as a substitute. Cut and remove the yarn with eggs after spawning.
Q: When do baby goldfish start to change color?
A: Most varieties begin changing at 2–3 months. Advanced breeds like Ranchu may take 6 months or more.
Key Takeaways for Breeding Goldfish
The secret to successful goldfish breeding is simple: simulate spring conditions, collect eggs promptly, and raise fry with care. With proper water temperature and quality, even beginners can enjoy raising a tank full of lively baby fish. Remember to allow parent fish at least six months to rest after each breeding cycle to keep them healthy for future spawning.
