Why Every Medaka Breeder Should Offer a Choice of Spawning Mops
7/4/20264 min read
Why Every Medaka Breeder Should Offer a Choice of Spawning Mops
One of the questions we're often asked at The Medaka Emporium is:
"What's the best spawning mop for medaka?"
The simple answer is... there isn't one.
Just as every medaka variety has its own unique beauty, individual fish also have their own preferences. Experienced breeders in Japan rarely rely on a single type of spawning mop. Instead, they provide several different styles and materials, allowing their fish to choose where they feel most comfortable laying eggs.
The result? More eggs, healthier spawning behaviour, and better fertility rates.
Medaka Can Be Surprisingly Selective
If you've ever watched your fish during the breeding season, you'll notice they don't always use every spawning mop you provide.
Some females will repeatedly return to one particular mop, while ignoring another sitting just a few centimetres away.
There are many reasons for this:
The texture may feel better against the eggs.
The strands may be the ideal thickness.
The colour may make the mop feel safer.
The movement in the water may be more attractive.
Some fish simply develop preferences through habit.
By offering a variety, you're letting the fish make the decision rather than forcing them into one option.
Different Materials Produce Different Results
There are now several popular styles of spawning media available, each with its own advantages.
Traditional Yarn Mops
The classic choice for most fish breeders. However, these are not suitable for medaka.
Abrasive Pad Strip Mops
These are the most popular choice amongst all medaka breeders. Also called scrub pads / scourers / brillo pads etc.
The coarse material provides countless tiny surfaces for eggs to attach to while remaining extremely durable. Many breeders find that all medaka fish readily choose these mops over ones made from yarn.
Advantages include:
Excellent water circulation
Easy to clean
Long lasting
Resistant to tangling
Fine Mesh or Net Mops
The soft mesh mimics the fine roots of floating plants.
Some females seem to enjoy weaving through the material before depositing eggs, particularly when spawning is at its peak.
These can be especially useful in ponds where gentle water movement keeps the fibres swaying naturally.
Made from either a tulle material or by cutting up shower puffs.
Black vs Green vs Blue
Colour isn't just for aesthetics.
Many breeders experiment with different colours because medaka can sometimes show a preference.
For example:
Black mops often create a darker, more sheltered appearance.
Green mops resemble aquatic vegetation.
Blue or teal mops are highly visible to the breeder when collecting eggs while still providing an attractive spawning site.
There is no universal "best" colour—the fish will decide.
Floating or Sinking?
Floating mops remain the most popular because medaka naturally spend much of their time near the surface.
However, depending on your setup, slightly deeper spawning mops can also be productive.
Providing both options allows fish to choose the depth they prefer on any given day.
More Choice Usually Means More Eggs
One of the biggest mistakes new breeders make is assuming that if a fish isn't spawning, they simply aren't ready.
Often, they just haven't found a spawning site they like.
Adding several different mop styles frequently results in:
Increased spawning activity
Higher egg counts
Better distribution of eggs
Easier collection
Reduced competition if keeping multiple females
Observe Your Fish
One of the most enjoyable parts of breeding medaka is watching their behaviour.
Try placing several different mop styles in the same tub.
Within a few days, you'll often notice patterns emerging. One variety may heavily favour a scrub pad, while another consistently chooses mesh.
Even different bloodlines of the same variety can behave differently.
The fish will usually tell you exactly what they prefer—you simply have to watch.
Our Advice at The Medaka Emporium
Rather than searching for the "perfect" spawning mop, we recommend building a small collection of different styles.
A mixture of materials and styles, in various colours, gives your medaka the greatest opportunity to choose a spawning site that suits them naturally.
Breeding success often comes from making small improvements, and providing choice is one of the simplest and most effective changes you can make.
Because at the end of the day, the best spawning mop isn't the one you think is best—it's the one your medaka choose.
Young Females Need Practice
If you're new to breeding medaka, don't be surprised if your younger females seem rather untidy with their eggs.
First-season females often scatter eggs individually around the pond or tub, dropping them on plants, algae, spawning mops, filter media—or even losing them altogether.
As they mature and gain experience, their spawning technique usually improves dramatically. Mature females are far more likely to carry and deposit their eggs together in neat, compact clusters, often resembling a small bunch of grapes, before attaching them to their chosen spawning site.
This is completely normal and one of the fascinating behaviours you'll notice as your breeding colony develops over time.
Don't Forget to Check Your Plants and Algae
Even with a selection of spawning mops available, some medaka simply have other ideas!
Certain females will ignore every mop in the tub and instead choose fine-leaved plants, floating roots, mosses, filamentous algae or blanket weed as their preferred spawning site.
For this reason, it's important to inspect all vegetation carefully when collecting eggs.
Before disposing of any algae or trimmings, always place them into a spare bucket or container of water and leave them for at least a few weeks.
You'll often discover newly hatched fry—that would otherwise have been thrown away. It's a simple habit that can save dozens of future medaka.
