Youtuber ThinFrog shares the secret to breeding goldfish in your own tank. In order to have his Ranchu goldfish breed, he uses something called a breeding mop.
When you think about fish breeding, you don’t normally think of it as connected to arts and crafts. But if you want to let your goldfish breed the natural way, you’ll need to pull out some yarn and a suction cup.
Use the yarn to create a breeding mop which you then tie to the suction cup. This is attached to the glass in your fish tank and provides a place for your goldfish to lay their eggs.