Zebra Danio Fact Sheet
The "Zebra Danio" or "Zebra Fish", "Brachydanio rerio" or "Danio rerio" is a very popular aquarium fish which comes from Eastern India and Bangladesh.
The Zebra Fish is often regarded as a cool water fish, but can survive in water of a very wide range of temperatures. I have heard reports of them surviving through the winter with pond temperatures as low as 4̊ C (39̊ F). This is the temperature water gets under ice. I do not recommend them as a pond fish for these conditions. At the other extreme, I have read that they can survive very high temperatures. Again, I would not suggest very high temperatures for the Zebra Fish although if a tank of these fish is infected with the white spot parasite, raising the temperature of the water to 34̊ C for two days will cure the fish and eradicate the disease from the tank. Make sure the fish have adequate aeration.
In practice, the Zebra Fish is happy in either cold water or tropical aquariums.
The "Leopard Danio" is sometimes given the scientific name "Brachydanio frankei" or "Danio frankei" but is not a true species, but rather a variation of the Zebra Fish. It crosses readily with the Zebra Fish producing fertile young. Care of these two fish is identical. The striped colouration of the Zebra Fish appears to act as a dominant single gene to the spotted pattern of the Leopard fish.
Hybrids can occur within the genus, but they are normally sterile.
The Zebra Fish grows to about 2 inches (5cm) long so it is a small fish. It is usually peaceful, but I’ve observed enough aggression in the Zebra Fish to class it as slightly aggressive, rather than peaceful. The Zebra Fish is a strongly schooling fish and, as with most schooling fish, they tend to be more likely to be aggressive if there is less than a school. I have known a school of Zebra Fish attack a Siamese Fighting Fish, so I would avoid slow moving fish with long fins in with Zebra Fish.
Suitable companions for the Zebra Fish include White Cloud Mountain Minnows, most tetras, including Neon Tetras, Cardinal Tetras, Glass Bloodfin Tetras, Emperor Tetras, Black Widow Tetras, small Goldfish and other similar sized fish.
Avoid slow moving, long finned fish like Guppies, Endlers Guppies and Siamese Fighting Fish.
The Zebra Fish is reasonably flexible in its water preferences, but I suggest near neutral to slightly acidic water. The hardness is not critical for the Zebra Fish. Zebra Fish do not like ammonia or nitrites, so the water should be kept clean and well filtered.
The Zebra Fish is very easily fed and are usually the first fish to come to the top to eat. It is an omnivore and will eat any normal fish food, and usually eat at the surface, but are happy enough feeding at any level of the aquarium.
As with other fish, they do better with a variety of food. I give mine frozen Brine Shrimp once a week. and frozen Blood Worms quite often as well as several different types of dry food. They love live food like Mosquito larvae and Daphnia.
Catching the Zebra Fish
If you can catch your fish before they are disturbed, the Zebra Fish is very easy to catch. They will swim into the net. However, once they are disturbed they are extremely good at evading capture. The horizontal stripes of the Zebra Fish combined with its speed of swimming make seeing it more difficult.
Occasionally an aquarium shop will have a competition to guess the number of fish in an aquarium on display. The fish chosen is usually the Zebra Fish because they are very difficult to count.
The Zebra Fish is easily conditioned because they eat so readily. Live Daphnia or mosquito larvae (wrigglers) are good. If these are not available, there are plenty of good dry and frozen foods. I use frozen bloodworms.
Zebra Fish are easily bred egg scatterers, and are also avid egg eaters. One common way of protecting the eggs is to have the water shallow with marbles or small rounded pebbles on the bottom. Most of the eggs will fall between the stones or marbles and have a chance of hatching.
Increasing the temperature a few degrees will often stimulate spawning. A temperature of about 26̊ C (78̊ F) is suitable for spawning the Zebra Fish. Eggs can hatch in a day. One female Zebra Fish will produce between 200 and 800 eggs, so the eggs and the fry that hatch from them are small.
The natural food of the Zebra Fish fry is protozoans (Infusorial) in the water. This can be supplemented with commercial fry food like Sara Micron. As the Zebra Fish fry get bigger they can eat larger grades of fry food like Sera Micropan or HBGFry Bites. Live food is very good including screened Daphnia or newly hatched brine shrimp.
With any pet. do not allow them to get into ecosystems that they are not native to.
Glofish™ are genetically modified Zebra Danios. Glofish are now available in six colours and three species of fish. They have had genes added from other species to make them glow fluorescently. They were developed as a first stage of a project to produce fish that would glow only in the presence of pollutants. The Glofish™ glow in all sorts of water; in the present form, they do not require pollutants to make them glow. The word ‘Glofish’ is a trademark and the rights to the fish is protected by law. Part of the purchase price goes into further scientific research.
Fluorescence is visible light being produced from invisible ultraviolet light. There is enough ultraviolet light in natural daylight, or in normal aquarium lights, to make these fish glow quite brightly. If you use an aquarium tube with a higher proportion of ultraviolet light, the effect is even more striking.
There are some impressive videos of Glofish at http://www.glofish.com/video.asp. Human, and fish eyes are more sensitive to blue light than the medium used in making these videos, so the aquarium would look lighter than these videos suggest.
These fish have had genes from other organisms added to their DNA, and breed true, in accordance with normal genetics. Apart from the fluorescence these are the same as normal Zebra fish.
Glofish™ are completely different from those fish that have had a dye injected into them.
Glofish™ are only available in the United States of America. California currently does not allow the sale of these fish. Australia, Canada, and Europe prohibit the marketing of genetically modified organisms.
There is no more risk of the Glofish™ becoming a pest than of normal Zebra fish becoming one.
According to the marketers of Glofish™ the Zebra fish has not become a problem in any part of the United States. They explain this apparent fact by saying that the Zebra Fish is a tropical fish and cannot survive in the temperate climate of the United States. Personally, I question this a bit. While the winters of the northern parts of the United States are fairly severe and are likely to kill Zebra Fish, the southern states, especially near the coast, would have winters well within the temperature tolerance of Zebra Fish. The basic point made by the sellers of Glofish™ is still valid. If the normal Zebra Fish has not become a problem there is no reason to expect Glofish™ to become established in the wild.
Sources and Picture Credits
The Veil tail zebra is from Fish Paradise. The Female Zebra Danio next to the breeding section is from Vivi's Animals. The newly caught wild Zebra Danio picture is from S3 Rare Fish. The long fin pink fish is from Betta fish animal Thailand. The Long fin Leopasrd danio is from Sweet Knowle Aquatics.