If you keep medakas, you know how exciting it is to discover eggs for the first time. But without the right tools, those eggs quickly disappear into the bottom or are eaten by the fish themselves. A mop is the solution: a simple but effective device that you can make yourself from ordinary yarn or foam. In this article I test four popular materials and explain step by step how to assemble your own mop. No expensive purchases necessary, just get started yourself!

Which material works best for wipe-off mops?

When making a mop, everything revolves around the structure of the material. Medakas stick their eggs to threads or fibers using small sticky filaments. The finer and softer the fibers, the better the eggs will stick. I tested four materials: 100% acrylic wool, polyester yarn, pool noodle strips and sisal rope. Each material has its own advantages and disadvantages, and the results were surprising.

Acrylic wool and polyester scored by far the best for egg adhesion. Sisal rope turned out to be too rough and coarse, so the eggs hardly stuck to it. Pool noodle strips in themselves are not suitable as a yarn substitute, but play another important role: they serve as a float for the mop. Below you can see an overview of the test results:

Comparison table: materials for wipe-off mops

Winner: 100% acrylic wool. This material has the finest fibers, is non-toxic to fish and can be easily found at any hobby store or online. Polyester is a good second choice, especially if you're looking for something that will last longer and be easier to clean. Avoid materials that have been bleached or contain synthetic dyes, as these can be harmful to both the eggs and the fish.

Floating or sinking mop: what suits you?

Not all medakas lay their eggs in the same place. In nature, medakas (Oryzias latipes) seek out aquatic plants on the surface, but in an aquarium or tank without plants they can also lay eggs on the bottom. Therefore, there is a distinction between them floating jokes and sinking jokes, and both have a specific application.

A floating mop mimics the surface layer where medakas naturally prefer to spawn. You attach the mop to a piece of pool noodle or cork so that it floats. This is ideal for outdoor tanks and aquariums where the fish actively swim on the surface. You simply lower a sinking mop to the bottom, sometimes with a small weight attached to it. This works well in deeper tanks or if you find that your medaka prefer the lower layers of water.

When do you choose which type?

Floating mop:

• Suitable for outdoor containers and ponds
• Ideal in summer when medakas are actively spawning on the surface
• Easier to check and remove daily
• Mimics aquatic plants such as waterweed or hornwort

Sinking joke:

• Suitable for deeper aquariums
• Handy if your fish are shy and prefer to spawn in the lee
• Can be combined well with a bottom layer of gravel or sand
• Less visible, which reduces stress on the fish

In practice, many medaka growers recommend using both types simultaneously. This way you give the fish a choice and increase the chance of successful egg deposition. I always use two floating mops and one sinking mop per container, and that works fine.

Make your own sales joke step by step

Now the fun part: get started yourself! You only need a little and it will take you no more than twenty minutes. Below you will find a complete materials list and assembly instructions for both a floating and sinking mop.

Materials list

For one floating mop:

• 1 piece of pool noodle (approx. 3 cm thick, 5 cm long)
• 100% acrylic wool or polyester yarn (unbleached, dark color works well)
• A pair of scissors
• A piece of fishing line or nylon thread (approx. 20 cm)
• A plastic fork or piece of cardboard as a wrapping template

For one sinking joke:

• 100% acrylic wool or polyester yarn
• A small stainless steel nut or pebble as a weight
• Nylon thread
• Scissors and wrapping jig

Assembly instructions: floating mop

1. Wrap the yarn around your wrapping jig about 50 to 70 times (a plastic fork works great).
2. Carefully slide the yarn off the mold and tie it securely in the center with a piece of nylon thread.
3. Cut the loops at both ends, leaving loose threads.
4. Push the nylon thread through the center of your pool noodle piece.
5. Tie the string so that the mop hangs securely on the float.
6. Shake the mop loose and fan the threads apart for a full, fluffy structure.
7. Rinse the mop thoroughly with cold water before use.

Assembly instructions: sinking mop

1. Follow steps 1 to 3 of the instructions above.
2. Instead of a float, tie a small stainless steel nut to the nylon string.
3. Check that the weight is heavy enough to allow the mop to sink to the bottom.
4. Also rinse this mop well before use.

Practical tip: Preferably use dark thread (green, brown or black). Medakas feel safer in dark colors and are more likely to spawn near the pug.

Frequently Asked Questions (FAQ)

How often should i remove the eggs from the mop?
Remove the eggs daily, especially in warm temperatures. Medaka eggs develop quickly (at 25 degrees Celsius in about 10 days) and if you leave them for too long the fish can eat them.

Can i use regular wool from the store?
Only if it is 100% acrylic or 100% polyester. Avoid wool of animal origin (such as sheep's wool) as it can promote mold and sometimes contains lanolin, which can be harmful to fish.

How do I clean a mop?
After use, rinse the mop with warm water without soap. You can also soak it briefly in a lukewarm salt bath (aquarium salt) to remove bacteria. Then let it dry thoroughly before reuse.

How many mops do I need per bin?
As a rule of thumb: use one mop for every five to ten fish. During an active spawning period in the summer, you can easily hang two or three moths in the tank at the same time.

My fish ignore the joke. What am I doing wrong?
Check that the mop has been rinsed thoroughly and does not emit any chemical odors. Sometimes it takes a few days for the fish to get used to it. Try moving the mop closer to the surface of the water or using a darker color of thread.

Making your own rip-off joke is really one of the most fun and satisfying jobs in the Medaka hobby. with a few euros in materials and half an hour of work, you have an effective tool that Will greatly increase your growing success. whether you choose a floating mop with pool noodle or a sinking version with a weight, the key is The right material: 100% acrylic wool is and remains The best choice. have fun growing, and enjoy every little bulb you find between the wires!