Zebrafish was originally found in the streams of Southern Himalayan in countries such as Pakistan, India, and Bangladesh among others. It lives in fresh water and initially inhabited canals, ponds, ditches, streams, and stagnant or slow-moving water. Zebrafish has propagated to other parts of the world such as Colombia and the United States of America. The following report will expound on specific autonomy, physiological, ecological, and behavioral aspects of the Zebrafish.
Zebrafish is named after the horizontal blue strips that run on its sides from its gills to the end of the caudal fin. This fish has a very interesting spindle-shaped form and a horizontally oriented mouth. It is easy to differentiate between a male and a female Zebrafish due to their structural differences. A female zebrafish has a larger belly that is whitish in color and posse’s silver strips that separate the blue strips. On the other hand, a male zebrafish has a smaller belly with golden strips that separate the blue strips. A female zebrafish has a small genital papilla that is located in front of where its anal fin originates. A zebrafish generally grows to 4 centimeters while under confinement although it is known to grow up to six centimeters when not confined. The lifespan of a zebrafish is about two to three years, although where conditions are excellent, they can live up to five years.
The generation time of a zebrafish is between three to four months. The ovulation and spawning of a female zebrafish occur only when a male is present. A female zebrafish can lay hundreds of eggs in each clutch every three days. The development of the embryo of a zebrafish begins immediately after the hatching of the egg and if the eggs are not fertilized, the development of the embryo stops after a few cell divisions. For those eggs that are fertilized, they turn transparent immediately and the development of the embryo continues rapidly. Within a time span of 36 hours after the fertilization of the eggs, the precursors to all main organs of a grown-up zebrafish appear. Thereafter, the hatching of the eggs occurs twelve to thirty-six hours after the appearance of all the precursors to all main organs of a zebrafish. The hatching of the eggs depends on the genetic composition of the embryo and the external temperature with 28.5 degrees Celsius being the optimum temperature for the hatching process. The feeding and swimming of a hatched zebrafish occur 36 hours after its hatching. The sex of the juvenile is not able to be distinguished at an early stage except by the dissection method, and sex determinants are not easily understood (Kimmel & Schilling, 1995).
The zebrafish is very instrumental in human genetics modeling as it helps scientists to study certain humans’ health conditions since it shares many genetics and anatomical human characteristics particularly in certain organs such as the heart and body plan. Similarly, its embryogenesis and anatomical features of the spinal cord, brain, and sensory systems closely relate with those of man. This similarity is the one that makes zebrafish genetics disorders resemble those disorders of man. As a result of these close biological and genetic similarities between human beings and zebrafish, zebrafish is widely used to examine biological questions and also to study human inherited diseases. For instance, zebrafish have many human biological characteristics, similar blood functions, and heart development. The development of the human embryo and that of zebrafish are similar. The zebrafish is very helpful in research work since its embryo develops outside the body and being transparent makes it very suitable for embryogenesis study. Some of the bodies of zebrafish are easily fluorescently labeled. This makes it possible for researchers to observe and study-specific tissues directly with the help of the fluorescence microscope. A female zebrafish can produce up to 300 embryos per week which makes it more possible to carry out significant statistical analysis at an avoidable cost. It is very helpful for high throughput screening therapies and drugs. The research of the zebra fish genome has enabled the researchers to identify strains that indicate mutations of some genes that are of interest to human diseases such as cancer (Kocher &, Jeffery, 2005). Zebrafish are very essential as they provide very suitable model for the study of behavior for both birds and mammals. They are very advantageous in the study of behaviors since their genetic effects on sense organ and brain development are well understood. Initially, scientists used mice for this study, but with the realization of the close linkage between the genetics and biological makeup of man and zebrafish, they preferred zebrafish as the most favorable genetics model for human health conditions because zebrafish posses’ relatively smaller brains than mice that makes them less complex to study. The study has enabled the discovery of the ability of the genes to play a major role in sensory or central elements of behavior regulations. A recent discovery through screening showed that a set of mutations affected the neural regulations of optomotor and optokinetic responses (Detrich, Westerfield, & Zion, 2011).
Despite the high importance of zebrafish as a human health genetic modeling, it is surprising to note that very minimal information is known about its behavioral and ecological information. The brief available data about the zebrafish indicate that zebra fish are widely distributed in tropical climates of India, Bangladesh, and Pakistan that posse’s monsoon climates accompanied with pronounced rainfall and very dry periods that affect the fish habitats greatly. Zebrafish are known to fare well in vegetative aquatic environments. Research indicates that zebrafish do well in water that is slightly alkaline with a ph value of 7-8. This ph value is important as it provides optimum conditions for the fish’s biological functions as well as the roles of the microbial community that is associated with good conditions favorable for the thriving of zebrafish (Lawrence, 2007).
Temperature plays an important role in the growth of zebrafish as a result of the great effect it have on the chemical processes and biological functions of a zebrafish. Zebrafish are noted to tolerate a wide range of temperatures. Zebrafish thrives in aquatic environments with a temperature range of 6.7 to 41.7 degrees Celsius. This tolerance is associated with the ability of the zebrafish to acclimate at a lower temperature for a period of time. Zebrafish prefers hard water. Water hardness is used to indicate the amount of divalent ions particularly calcium and magnesium present. These ions are very important for fish since they affect their biological functions. For instance, Calcium is very important to zebrafish as it is required by zebrafish for blood clotting, ossification and some physiological and biological functions. Similarly, water hardness may also affect the pathology of particular diseases and also osmoregulations of zebrafish. The fish is known to tolerate a wide range of water hardness.
Salinity is another very important aspect of zebrafish. It is important because it affects the amount of energy that the fish uses to gain water and lose salt through diffusion process across their gills and skins. Therefore, for them to use less energy they require to maintain a balance in their internal water and salt by excreting copious of dilute urine while at the same time transmitting ions into their bodies. If the water salinity is not conducive for the fish, the fish tends to consumer a lot of energy that affects negatively their survival, reproduction and growth. The zebrafish are freshwater fish, but can tolerate a wide range of salinities (Lambert, 1997).
Zebrafish requires great amount of oxygen due to their small sizes and high metabolic rates. The availability of oxygen in the water varies depending on water temperature, quality and salinity. Nitrate dissolved in water can often be very poisonous to fishes. Nitrates are produced during the decomposition of decaying uneaten foods or dead fish. Fish are not affected by nitrates at lower levels, but when nitrates accumulates into higher levels they are at they may be dangerous to some fish species. The zebrafish is not affected by nitrate even at higher levels. The dieting of zebrafish is very important for them to thrive well. The zebrafish should be fed with all the required nutrients in order to grow and reproduced well. When it is noted to lack some nutrients, the missing nutrients should be provided through artificial supplements to enhance their survival, growth and reproductions (Wakulla, 1987).
References
Detrich, W., Westerfield, M. & Zion, L. (2011). The Zebrafish: Genetics, Genomics and Informatics. Web.
Kimmel, C. & Schilling, T. (1995). Stages of embryonic development of the zebrafish. New York: Prentice Hall.
Kocher T. &, Jeffery, W. (2005). Special feature: Fish models for studying adaptive evolution and speciation. New York: Prentice Hall.
Lambert, J. (1997). Freshwater Aquarium Fish. Edison, New Jersey: Chartwell Books.
Lawrence, c. (2007). The husbandry of zebrafish. Web.
Wakulla, M. (1987). Ecological and Behavior of Zebrafish. London: University Press.