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Zebra Danio

Scientific Name: Danio rerio
Family: Cyprinidae, Sub-Family Rasborinae

About the Zebra Danio

Species Type: Freshwater Fish
Category: Cyprinids

Care Level: Very Easy. Will tolerate a wide range of water parameters including pH, temperature and hardness. Can tolerate higher nitrate levels than other fish and is hardy enough to withstand the cycling process. Will readily eat prepared foods and has no special care requirements.

Origin: India, Bangladesh and possibly Bhutan; some authors doubt early reports of its natural occurrence in Pakistan and Myanmar. Engeszer's 2007 survey indicates this fish inhabits calm, shaded areas in streams and smaller rivers, moving into seasonal tributaries and pools to spawn during the monsoon season.

Compatibility/Temperament: A very peaceful shoaling fish, that must be kept in groups of at least six and preferably more. It can be combined with any non-aggressive fishes, but given its active nature should not be kept with sedate fish (gourami, angels, etc).

Description

This fish is one of the most popular and a long-time favorite among hobbyists owing to their hardiness and adaptable nature. They will show their best colouration in a group in a well-planted aquarium with floating plants to shade the light. As noted under Compatibility, they are active swimmers and should not be housed with slow, sedate fish as they will not only make them uneasy but may have a tendency to nip their fins.

Contrary to what some maintain, they do not require a strong flow from the filter [note the above description of their habitat]. However, provided it is not too strong, they can manage and make suitable tankmates for many of the smaller loach species.

Zebra danios are easy to spawn; like all danio species, they are egg scatterers and will readily eat their eggs. Females are rounder, slightly larger and a bit less colourful than males. Provide a spawning tank with thickets of fine-leaved plants or put the water level to half and place a deep bed of marbles, preferably 5-6 cm deep, so the eggs will slip unscathed. As these fish are among the easiest of the cyprinids to breed, breeding requires little effort by the aquarist. The fish has a lifespan of five years. It swims at all levels in the aquarium.

The leopard danio, sometimes seen under the name Danio frankei, is probably a man-made colour morph variation; most authorities agree that this variant has not been found in nature. The right photo above shows this fish. Of more distress to many is the genetically modified form known as glofish that are now being produced in the United States; these have been banned from import by the European Union of countries.

The species was originally described by F. Hamilton in 1822 under the name Cyprinus rerio, but was moved into the genus Danio and then Brachydanio. As detailed below, the species is now valid as Danio rerio (Hamilton 1822) though it still appears in older literature under the former name.

The danionin is a group of minnow-like fish within the family Cyprinidae. All discovered species were originally placed in the genus Danio until Dr. George S. Meyers (in the early 20th century) divided them into three genera, Danio, Brachydanio and Daniops. During the latter two decades of the twentieth century, many ichthyologists had doubts about the validity of Brachydanio, and in 2003 Dr. Fang Fang in her study "Phylogenetic Analysis of the Asian Cyprinid Genus Danio (Teleostei, Cyprinidae)" determined that the genus Danio was paraphyletic [Greek para = near and phyle = race], which means the genus contains its most recent common ancestor but does not contain all the descendants of that ancestor. Danio was restricted to the nine species of the Danio dangila group comprised of the smaller-sized species, and the genus name Devario was suggested for the remaining larger-sized species. The former genus Brachydanio was disbanded.

Several further developments in research occurred in the subsequent years, and two significant studies were published in 2007: "Evolution of miniaturization and the phylogenetic position of Paedocypris, comprising the world's smallest vertebrate" [Lukas Ruber, Maurice Kottelat, Heok Hui Tan, Peter KL Ng, and Ralf Britz] and "Phylogenetic relationships of Danio within the order Cypriniformes: a framework for comparative and evolutionary studies of a model species" [Richard L. Mayden, Kevin L. Tang, Kevin W. Conway, Jorg Freyhof, Sarah Chamberlain, Miranda Haskins, Leah Schneider, Mitchell Sudkamp, Robert M. Wood, Mary Agnew, Angelo Bufalino, Zohrah Sulaiman, Masaki Miya, Jenji Saitoh, and Shunping He]. This latter work recognized the close relationship of Microrasbora species to those of Danio.

In Joseph S. Nelson's "Fishes of the World" (2006), Danioninae was listed as a synonym of Rasborinae. It is generally held (though some disagree) that there are three clades within the genus Danio, and the danionin genera are within the Sub-Family Rasborinae [having priority over Danioniae] along with several genera of rasborin. The danionins can be classed as a subfamily Danioninae which is increasingly gaining credibility as a distinct subfamily from Rasborinae within the Cyprinidae family. We follow Dr. Fang's placement as the most plausible, though many speculate that the clades may end up as distinct genera.

Zebra Danio Diet

These fish are omnivorous and are not fussy when it comes to food. They will appreciate a wide range of diet including prepared foods, frozen bloodworms and daphnia, and live worms and insects.

Size

Attains close to two inches maximum.

Minimum Tank Suggestion

24 inches in length; this species requires room to swim.

Ideal water parameters for Zebra Danio

Soft to moderately hard (hardness to 20 dGH), acidic to basic (pH 6.0 to 8.0) water, temperature 18-25C/65-77F.

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Zebra Danio 1
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Zebra Danio 2


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