All about Zebra Fish: Characteristics, habitat, employ in labs and more…

All about Zebra Fish (Danio rerio) is a tropical freshwater fish that is very popular among aquarium lovers. If you want to learn all about it don’t miss this article.

Zebra Fish Review

Just over 30 years ago Zebra Fish were introduced as a model species for research in the field of developmental biology and genetics. Since then, hundreds of laboratories around the world analyze this fish, which is also very useful for the study of human biology.

Genetically, the zebra fish are more similar to the human species than the vinegar fly or the worm and are easier to manipulate, maintain and breed than the mouse. In 2002, the Wellcome Trust Sanger Institute published on the Internet the first draft of the sequence of the zebrafish genome, which includes some 17,000 genes.

 

All about Zebra Fish: Main Characteristics

Zebra Fish are small fish since adult individuals are usually between 3 and 5 cm long and 1 cm wide depending on environmental conditions. Their body has an elongated shape with a dorsal fin. Moreover, there are between 5 and 9 bluish bands on their sides that overlap to their background color that in the males is golden and silver in the females. This striped look is the main reason of their names. We invite you to read our article the anatomy of fish to learn more about such a topic

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All About Zebra Fish: Where do Zebra Fish Inhabit?

Zebra Fish inhabit in more or less quiet waters, sometimes stagnant, from central Asia, especially in Ganges (India). However, they can also be found in the rivers of Nepal, Bangladesh, Pakistan and Myanmar.

They are omnivorous creatures that feed on mosquito larvae, zooplankton and microscopic algae (phytoplankton). In aquariums, they must be kept at a temperature range between 22 and 30 ºC, a neutral pH (~ 7) and from 5º to 10º dGH of hardness.

All About Zebra Fish: The Zebra Fish’ Common Behavior

Zebra fish are quiet and social creatures that tend to make-up small groups. They coexist with other species of the same genus, such as the blue danio (Danio kerri), the Purple passion Danio (Danio roseus), and the needlefish (Microphis sp). Among their possible predators we can mention the snakehead fish (Channa sp.),

All About Zebra Fish: Life Cycle and Reproduction

In their natural habitat the mating season takes place between April and August. Zebra fish are oviparous species and the laying of the eggs occurs on the banks of the rivers. The eggs usually hatch in three days from fertilization and at five or six months individuals reach reproductive maturity. In the laboratory, females can lay between 200 and 300 eggs, while the embryonic development takes place in 24 hours and the larvae begin to feed by their own within five days.

All About Zebra Fish: Eating Habits

Zebrafish  are omnivorous creatures that get most of their food from the water column of the seas, mainly zooplankton and aquatic insects. In Addition, they also feed on the surface of the water, devouring terrestrial insects and small arachnids, mosquito larvae being one of their favorite meals.

All About Zzebra Fish:The success of the Zebra Fish in Labs

Zebra fish are being investigated in hundreds of laboratories and by thousands of researchers around the world. They are considered a key instrument in biomedical and environmental research since they share a remote common origin with humans (400 million years ago). In addition, their maintenance is relatively economic and because they can help to reduce the use of mammals in experimentation. This species has achieved a privileged position, like that of more traditional species like the fly of vinegar and the mouse.

The publication of the sequence of their genome has arrived with some delay, because only recently (2008) an almost complete version has been obtained.  In a 20 liters tank, up to one hundred fish can be raised. A female can lay up to 300 eggs in a day, week or every fortnight depending on whether the conditions in the laboratory are more or less favorable.

The embryos measure less than 1 mm, allowing large quantities to be placed on a single plate (embryo observation device) to follow their development. The embryos development takes place in 24 hours, and most of their organ can be easily recognized. Perfecto has ta aca

After five days the larvae are mobile, they have finished consuming most of the yolk and the exogenous feeding begins. This characteristic is important because under the current legislation on animal experimentation a fish is considered animal since exogenous feeding begins.

It has been observed that in the zebrafish it happens from the five days of development. Therefore, the use of zebrafish embryos up to that time-(is the period in which most trials are performed)-is considered an alternative method and no animal experimentation.

Fluorescent and Transgenic fish

The transparent embryos of the zebrafish can also be used to study the morphology and physiology of certain groups of cells by fluorescent probes and antibodies from immunohistochemical staining techniques and in situ hybridizations.

A more sophisticated technique is to insert into the embryos transgenic constructions that carry a fluorescent protein (Green Fluorescent Protein, PVF or GPF in its English abbreviations, extracted from the jellyfish Aequorea victoria) bound to a specific DNA sequence (promoter) of the tissue that  you want to observe (muscle, thyroid, lateral line).

The PVF-promoter constructs are called transgenes and the animals that carry them are transgenic animals. The promoter is a piece of DNA that acts as a switch, activating or deactivating the action of a gene. These constructions or transgenes allow seeing the differences between normal fish and fish in which the function of a gene has been altered.

The zebrafish as an experimental material allows the systematic identification of new drugs and the observation and analysis of the effects of drugs and toxic products throughout the body.

For this reason, in the fields of pharmacology, toxicology and ecotoxicology, this species is proposed as an effective intermediate step in the drug development process and as a very fine system to detect the toxicological effects of both new products synthesis as of the contaminants emerging from the environment.

New drugs Identification

The small size of the zebrafish embryos makes it possible to speed up the analysis of an extensive collection of candidate molecules to be a new drug and its identification, this being one of the most arduous phases of the drug development process.

In addition, these analyzes are performed in a living system and allow to see the effects throughout the body. This allows, on the one hand, overcome the limitations of cellular tests that don’t  always meet the conditions «in vivo» and, on the other hand, avoid having to resort to the use of mammals in the early stages of drug development, while being more economical.

Tissue regeneration

Unlike mammals, the zebrafish has the ability to regenerate some tissues such as the nervous, tissue of the heart, the retina or the ear. Investigating the mechanisms that act in the regenerative process deploys new opportunities for repairing injured tissues in humans.

It is necessary to take into account how regenerative activity has been maintained in the evolutionary line of vertebrates and establish, through genomic analysis, the genes involved in that process. The idea is that one could act on orthologous genes in mammals to «reactivate» the lost regenerative activity.

Model system for studies of function and gene regulation

The zebrafish is excellent for the development of relevant genomic studies for human health. Since all vertebrates evolve in a similar way during the early stages of embryonic development, this model allows us to study the function of genes involved in processes that take place during the early development of all vertebrates, including humans.

Also, it has been revealed as a powerful system to carry out gene regulation studies «in vivo». The “cas” regulation sequences (control at the same chromosome level) control where and how genes are transcribed and can activate (activator) or repress (silencing) gene expression. By generating transgenic fish in which these sequences control the expression of the Fluorescent Green Protein, PVF, the activity of such regulatory sequences can be visualized «in vivo».

The fish memory

The zebrafish is a social animal; therefore, it can be useful to investigate behavioral genetics. In addition, it has a diurnal behavior which allows measurements to be made in the natural time of activity. In the adult the molecular basis of reward seeking behavior is being investigated as a starting point for addictions and issues related to learning and memory. At the larval level, the capture of prey serves to study simple behaviors such as locomotion and vision.

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