How to Make DIY Spawning Mops for Breeding Aquarium Fish

Many aquarium fish like to lay their eggs by scattering them or sticking them onto plants and various surfaces. To protect the eggs from being eaten and improve the survival rate of baby fish, veteran breeders often make spawning mops for the fish to deposit their eggs. Unlike live aquarium plants, this artificial spawning media does not require any light or fertilizer, and they are quite easy to transport without breaking any plant leaves or roots. People even use them with livebearers (or fish that bear live young) because the many strands of the mop provide dense cover for the fry to hide between. Follow these simple, step-by-step instructions for making two types of spawning mops for your aquarium fish.

Instructions for Yarn Spawning Mop

This popular type of spawning mop is commonly used with goldfish, rainbowfish, tetras, barbs, killifish, and more. Depending on the species you are breeding, you can make a floating mop, sinking mop, or a mop that attaches to the tank wall.

1. Gather the materials:
   1. 100% acrylic yarn
   2. Cork (for a floating mop), small rock (for a sinking mop), or suction cup (for a mop that attaches to the tank wall or bottom)
   3. Hard, flat object that is the desired height of the mop (e.g., notebook, book, Blu-ray case, or piece of cardboard)
   4. Scissors

2. Wrap the yarn around the notebook about 40 to 100 times and then cut off the rest of the yarn.

3. Cut a 12- to 24-inch length of yarn and use it to tightly knot together the yarn strands wrapped around the notebook.

4. Slide the yarn strands off the notebook and cut the loops at the opposite end of the yarn knot. Trim the mop if the yarn strands are uneven or too long.

5. Take the excess ends of the knot and securely tie them around the cork, rock, or suction cup.

6. Rinse the mop in tap water without any soap and place it in the aquarium.
7. Depending on the species, wait a few days to a couple of weeks after the fish have been spawning. Then move the eggs in the spawning mop into a breeder net or specimen container that has a gentle air stone in it. Some people transport the entire spawning mop with the eggs, while others like to pick out the eggs with their fingers or tweezers.

Instructions for Ricefish Spawning Mop

Regular yarn mops do not work as well for certain species like Japanese medaka ricefish because the yarn strands are too free-flowing. Rice fish need stiffer bristles to rub against in order for the eggs to come off.

1. Gather the materials:
   1. Pool noodle with a hollow hole in the center
   2. Scotch-Brite pads (with no cleaning chemicals in them)
   3. Kitchen knife and cutting board
   4. Scissors

2. Slice off a ½-inch circle of the pool noodle using a knife and cutting board.

3. Take one pad and position it in a horizontal, landscape orientation so the pad is wider than it is taller. Starting from one of the bottom corners of the pad, make a vertical cut upwards and stop roughly ½” from the top. Make multiple vertical cuts every ¼” along the bottom of the pad, thus creating the “strands” of the mop.

4. Roll up the pad so that the top ½” of the pad looks like a spiral, while the bottom “strands” of the pad spread out like a skirt.

5. Stick the spiral end of the mop through the middle of the pool noodle disc.

6. Rinse the spawning mop without any soap and place it in the aquarium.

7. After spawning has occurred, move the eggs or the entire spawning mop into a breeder net, specimen container, or separate grow-out tank.

Best of luck with your breeding projects. If you have hatched and raised too many fish, consider selling them to your local fish store or other fishkeepers to help support your aquarium hobby. Learn more in our article on How to Breed Aquarium Fish for Profit.