Two major considerations in breeding GloFish, a genetically modified variety of the tropical zebra danio fish, are to keep the eggs from being consumed by the fish for food and to make sure they are not swept into the tank's air filter. Zebra danio lay eggs that do not adhere to a surface, so protecting them is the primary goal in successful breeding.
One method of protecting GloFish eggs is lining the bottom of the tank with a double layer of marbles. The eggs fall into the cracks between the marbles where the fish can not eat them; the marbles also keep the eggs from being sucked into the filter. After the eggs spawn, the adult fish should be removed from the tank.
Another tip is to use a breeding net. Place the fish over the net until breeding occurs, letting the eggs fall through the net. Once the eggs are on the bottom of the tank, remove the fish.
A fresh change of water may also encourage breeding. The water should be kept at 78 to 82 degrees Fahrenheit. A ratio of two males to each female increases the odds of breeding. GloFish is a patented brand of fish that is protected by license against being bred for sale, barter or trade. However, breeding of GloFish is allowed for educational purposes.