[1][11][12][13] The northern limit is in the South Himalayas, ranging from the Sutlej river basin in the Pakistan–India border region to the state of Arunachal Pradesh in northeast India.

[13][14] It has frequently been said to occur in Myanmar (Burma), but this is entirely based on pre-1930 records and likely refers to close relatives only described later, notably Danio kyathit.

[15] Zebrafish have been introduced to California, Connecticut, Florida and New Mexico in the United States, presumably by deliberate release by aquarists or by escape from fish farms.

[12][19] Zebrafish typically inhabit moderately flowing to stagnant clear water of quite shallow depth in streams, canals, ditches, oxbow lakes, ponds and rice paddies.

Zebrafish are asynchronous spawners[25] and under optimal conditions (such as food availability and favorable water parameters) can spawn successfully frequently, even on a daily basis.

[28] Exposure to environmentally relevant concentrations of diisononyl phthalate (DINP), commonly used in a large variety of plastic items, disrupt the endocannabinoid system and thereby affect reproduction in a sex-specific manner.

As the larvae develop, from 15 dpf onwards, they are typically transitioned to a diet that includes brine shrimp nauplii and dry feeds, which are more nutritionally balanced and easier to manage in laboratory settings.

For larvae aged 25 dpf, feeding rates can range from 50% to 300% of their body weight (BW) per day, depending on their size and growth requirements.

This structured approach to feeding not only supports optimal growth and health but also enhances the reliability of experimental outcomes in research settings[33] Zebrafish are hardy fish and considered good for beginner aquarists.

[55] In 2011, the British Heart Foundation ran an advertising campaign publicising its intention to study the applicability of this ability to humans, stating that it aimed to raise £50 million in research funding.

[56][57] Zebrafish have also been found to regenerate photoreceptor cells and retinal neurons following injury, which has been shown to be mediated by the dedifferentiation and proliferation of Müller glia.

[59][60] In 2012, Australian scientists published a study revealing that zebrafish use a specialised protein, known as fibroblast growth factor, to ensure their spinal cords heal without glial scarring after injury.

[68] Another focus of zebrafish research is to understand how a gene called Hedgehog, a biological signal that underlies a number of human cancers, controls cell growth.

Inbred strains and traditional outbred stocks have not been developed for laboratory zebrafish, and the genetic variability of wild-type lines among institutions may contribute to the replication crisis in biomedical research.

[71] Due to their fast and short life cycles and relatively large clutch sizes, D. rerio or zebrafish are a useful model for genetic studies.

[76] Despite the complications of the zebrafish genome, a number of commercially available global platforms exist for analysis of both gene expression by microarrays and promoter regulation using ChIP-on-chip.

In December 2005, a study of the golden strain identified the gene responsible for its unusual pigmentation as SLC24A5, a solute carrier that appeared 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 strongly segregate fair-skinned Europeans and dark-skinned Africans.

This involved creating a transgenic zebrafish line expressing a fluorescent protein under the control of a heavy metal-responsive promoter, enabling the detection of low concentrations of cadmium (Cd2+) and zinc (Zn2+).

[93] In January 2013, Japanese scientists genetically modified a transparent zebrafish specimen to produce a visible glow during periods of intense brain activity.

[8] In January 2007, Chinese researchers at Fudan University genetically modified zebrafish to detect oestrogen pollution in lakes and rivers, which is linked to male infertility.

Exposure of zebrafish to environmental stress induced by the chemical clotrimazole, an imidazole fungicide used in agriculture and in veterinary and human medicine, amplified the effects of inbreeding on key reproductive traits.

Zebrafish are common models for research into fish farming, including pathogens[98][99][100] and parasites[98][100] causing yield loss or spreading to adjacent wild populations.

[110] Using smart data analysis methods, pathophysiological and pharmacological processes can be understood and subsequently translated to higher vertebrates, including humans.

In another study, an effort was made to therapeutically target the genetic program present in the tumor's origin neural crest cell using a chemical screening approach.

[115] This revealed that an inhibition of the DHODH protein (by a small molecule called leflunomide) prevented development of the neural crest stem cells which ultimately give rise to melanoma via interference with the process of transcriptional elongation.

In 2007, researchers at University College London grew a type of zebrafish adult stem cell found in the eyes of fish and mammals that develops into neurons in the retina.

[141] The Machuca-Tzili and co-workers applied zebrafish to determine the role of alternative splicing factor, MBNL, in myotonic dystrophy type 1 (DM1) pathogenesis.

[142] More recently, Todd et al. described a new zebrafish model designed to explore the impact of CUG repeat expression during early development in DM1 disease.

As an example, transgenic zebrafish with overexpressed AgRP, an endogenous melanocortin antagonist, showed increased body weight and adipose deposition during growth.