We have two goldfish in a fish tank; a female and a male bronze fantails.
Last spring, they laid egg! Yay!
In this article I will write about what we did to help prepare goldfish to lay egg in the spring.
Goldfish Breeding Season:Spring – Autumn
Breeding season for goldfish is thought to be anytime between spring – autumn in area where there are four seasons.
Water temperature needs to be 20°C (68°F) or above and stable for goldfish to breed.
For outdoor goldfish, goldfish tend to breed in spring, when the temperature start to rise.
Signs of Goldfish Preparing to Lay Eggs
There are a few signs that tells you goldfish are ready to lay egg.
1. There are white star-like pimples on the male goldfish
A sexually mature male goldfish will develop white pimple-like marks on their face and often also on the front fin.
They appear similar to star-shaped white pimples.
Spotting these star-shaped pimples is often the best way to distinguish a male goldfish from a female.
These star-shaped white pimples will appear more strong and distinct when the male goldfish is in breeding season.
2. Female goldfish will become more round
As breeding season start, a female goldfish will start to get slightly more rounder in shape, especially around her abdominals.
This is because female goldfish are starting to produce and store egg in their bellies.
3. Male goldfish start chasing female goldfish
Male goldfish start “chasing” female goldfish when both parties are ready to lay egg.
This is often accompanied by a male goldfish trying to poke belly of the female goldfish.
This is a male goldfish trying to “stimulate” female goldfish to lay egg, and a very strong sign that goldfish are ready to lay egg.
So if you see a goldfish chasing after another goldfish, and the chasing goldfish has white star-shaped pimples on it, that means you have a breeding male and female goldfish ready to lay egg.
You should put some suitable aquatic plants for the female goldfish to lay eggs on, and you may see transparent small eggs soon!
Conditioning your Goldfish for Breeding
As for our bronze fantail goldfish, I knew one was a male and the other was a female when I bought them from a local pet shop.
But as the spring arrived… they did not show any signs of “chase” between them.
So in order to promote their breeding behavior, I did some research and tried the followings.
１．Changing fish tank water
Often people talk about how changing the water of the fish tank promotes breeding in goldfish.
Changing a large proportion of tank water can be very stressful for the goldfish, and it puts them into a kind of “high” from stress.
Apparently, this “high” can stimulate male goldfish to start “chasing” female goldfish.
２．Let indirect sunlight to the fish tank
At my home, my fish tank is placed indoor near the window.
But the window always had heavy curtains that were always closed.
Curtains were closed to prevent sunlight from hitting the fish tank, but because of them, fish tank was always in a dim place.
But natural light can serve as a cue for living creatures to learn the change in seasons, as day light get longer in spring and shorter in the autumn.
So I tried opening the curtain every day to let some more natural light reach the fish tank.
Thin curtain is still closed and no direct sunlight will hit the fish tank.
After I started letting more natural light onto the fish tank, goldfish started to look more livery.
Although it might be just me thinking they look lively, I think that this had some positive effect on their breeding behavior.
３．Placed HEAPS of soft aquatic plants like Cabomba
Goldfish lay their egg on aquatic plants – so having aquatic plants in the fish tank is a requirement for breeding goldfish.
From the start, I always had aquatic plants in my fish tank.
But the type of aquatic plant I had was one with normal, firm leaves, rather than some aquatic plant with really soft leaves.
So I though that maybe, the type of aquatic plant I had in my fish tank was not very preferable for my goldfish to lay egg.
For laying eggs, goldfish prefer aquatic plants that are really soft like cabomba.
You can try making your own artificial cabomba-replacement by making a fir-ball from soft cotton strings or vinyl strings.
I think the natural aquatic plants are the best, so I went and got a large quantity of cabomba-like aquatic plants and placed them in the fish tank.
I made sure there were plenty too; there were about 4 bundles of plant (about four long stems of cabomba per bundle) with weights on one end.
Plus, there were some more loose cabomba floating on the top of fish tank.
Placing plenty of cabomba-like aquatic plant had a visible effect on my goldfish behavior.
Female goldfish started swimming near the aquatic plants, putting her head into aquatic plant leaves and pocking the leaves.
Female goldfish got really busy checking out aquatic plants; she actually looked like she was enjoying the new, soft aquatic plant bed.
Cabomba-like aquatic plants (Cabomba-like as as I am not 100% sure this is cabomba).
After letting some natural light on the fish tank (above 2) and putting new soft aquatic plants (above 3), female goldfish started to show signs of breeding; like rubbing her body against aquatic plants.
４．Feed Goldfish Twice a Day
I was talking to someone who breeds zebra fish and mountain minnows, and she always feeds her fish twice a day; in the morning and late afternoon.
Apparently, feeding twice a day works better for breeding zebrafish than feeding just once a day.
So I feed my goldfish twice a day now, thinking that it might work better for breeding goldfish too.
I am not sure if it had any effect on my goldfish breeding, but at least there was no obvious bad effect.
Preparing for Breeding Goldfish: Summary
So…. to summarize what I tried to get my goldfish ready for breeding…
１．Must have a male and a female goldfish at least!
３．Feed goldfish twice a day
４．Let some natural light for indoor fish tank; so goldfish can feel seasonal change (no direct sunlight!)
５．Put plenty of soft aquatic plants (cabomba is perfect) as egg-laying-bed for goldfish ←probably most important!
In the end, my goldfish managed to lay some eggs – I am writing other articles about their development and growth.
Goldfish egg day 0 ~ hatching