Zebra Danio

Danio rerio or Zebrafish is a tropical fish belonging to the minnow family (Cyprinidea), commonly kept in aquaria and used for scientific research. The fish is named for its five uniformly, pigmented, horizontal blue stripes on the side of the body; all extending to the anal fin onto the end of caudal fin rays of its tail. Zebra Danios are of no economic importance in commercial fisheries as a food fish, but very commonly known and popular in the aquarium trade. They are hardy fish and considered good for beginner aquarists. This species has been called one of the "bread and butter" fishes because of its ease of keeping, continued popularity and its favorable price and availability.

Originating in Eastern India as well as in Pakistan, India, Bangladesh, Nepal and Myanmar, it grows to about 2 inches (6 cm) and lives for around 5 years. The zebra danio, in its native range, commonly inhabits streams, canals, ditches, ponds and also occurs in slow-moving to stagnant water bodies, particularly rice fields. In the aquarium trade, there are long-finned and other color forms of this danio, including a "Leopard" danio.

Like other danios it is omnivorous and a peaceful fish that gets along well with other fish of similar size in community tanks. A schooling fish, it prefers to be in groups of six or more. Zebra Danios prefer water with a 6.0–8.0 pH, a water hardness of up to 5.0–19.0 dGH, and a temperature range of 64–74 °F (18–24 °C).

The males have gold stripes between the blue stripes and females have silver stripes instead of gold. An egg-scatterer, danios produce around 100 eggs in a single spawning. They are considered one of the easiest aquarium fish to breed.

Other fish also share the name zebrafish.

Diseases

Zebra Danio are susceptible to Oodinium, or Velvet disease.

Feeding

Zebra Danios are omnivorous. In the wild, these fish consume various small aquatic insects, crustaceans, worms as well as plankton. For this reason, they can be used to reduce mosquito larvae populations in ponds and ditches. For zebra danios living in aquaria, live/frozen flaked foods are suitable, especially brine shrimp and sinking tablets. When conditioning zebras for breeding, it's advisable to feed them plenty of fresh foods.

Model organism for development and genetics

Zebra Danios serve as a common and useful model organism for studies of vertebrate development and gene function because they reproduce very easily, passing from the egg to the larvae stage in less than three days. For genetic research groups, the zebrafish is an excellent test subject and is used in many labs to replace or to supplement higher vertebrate models, such as rats and mice. Danio rerio is one of the few species of fish to have been flown into space (See Animals in space). Aided by the transparency of the embryo, if researchers modify the fish's genotype at the egg stage they can see resulting changes in organ shape or dynamics barely three days later. The arrival of zebrafish as a major model for studying developmental biology co-incided with a large scale mutagenesis screen (commonly referred to as the Tübingen screen). The scholarly journal Development devoted an issue to research using the fish in celebration of this landmark. ^{A common reverse genetics technique is to knock down gene expression or modify splicing in zebrafish using Morpholino antisense technology; the journal ^*}, mostly in Danio rerio.

In addition, zebrafish have the ability to regenerate almost any organ in their body . Researchers frequently cut the dorsal and ventral tail fins and analyze their regrowth to test for mutations. This research is leading the scientific community in the understanding of healing/repair mechanisms in vertebrates.

The results of genetic engineering in these fishes have been used to produce the Glofish, an aquarium pet with fluorescent pigments. Other varieties include golden, sandy and long fin fish.

In December 2005, a study of the golden strain identified the gene responsible for the unusual pigmentation of this strain as SLC24A5, a solute carrier that appears to be required for melanin production, and confirmed its function with a Morpholino knockdown. The orthologous gene was then characterized in humans and a one base pair difference was found to segregate strongly between fair skinned Europeans and dark skinned Africans. ^{^*} This important study featured on the cover of the academic journal Science and demonstrates the power of zebrafish as a model organism in the relatively new field of comparative genomics.

Zebra danios as an introduced species

Zebra danios have been introduced and become established in Japan and the United States. The fish has also been sighted in Colombia, presumably escaped from an aquarium fish rearing facility and into local waters.

Former Names and Synonyms

Barilius rerio
Cyprinus chapalio
Brachydanio rerio
Cyprinus rerio
Danio lineatus
Nuria rerio
Perilampus striatus

External links

References

Zebrafish information network

Model organisms | Cold-water aquarium fish | Danios

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