9/2/2023 0 Comments Breed zebra danios![]() ![]() Zebrafish are promiscuous and breed seasonally during monsoon season. Sex determination is not fully understood however, evidence suggests that food supply and growth rates play a key role in sex determination as slow-growing individuals become males and fast-growing individuals become females. Once they become five to seven weeks old, gonadal differentiation begin to occur, Males take approximately 3 months to fully develop their testes. Immediately after hatching, all zebrafish develop into females. Range length 64 (in captivity) (high) mm in.( Albertson and Kocher, 2006 Mayden, et al., 2007 Spence, et al., 2008) The degree of sexual dimorphism in zebrafish is minimal, as males tend to have more yellow coloration and tend to have larger anal fins than females. Zebrafish have several defining features including an incomplete lateral line, two pairs of barbels, and several (usually 5 to 7) longitudinal stripes along the sides of their body. Additionally, they are obligate suction feeders. As a result, they rely on gill rakers to break up food. Like other cyprinids, zebrafish are stomachless and toothless. They have centrally located eyes and thin elongate mandibles with a protrusive lower jaw that causes the mouth to point upwards. ![]() The largest recorded zebrafish reached 64 mm in captivity. Zebrafish have fusiform, laterally compressed bodies that reach an average length of 25 mm. Fortunately, zebrafish are relatively tolerant of human disturbance and are able to survive and reproduce well in altered habitats. Since rice farming is common in India, many natural habitats of zebrafish have been dramatically altered by damming and irrigation. Rice farming requires damming of waterways and creation of irrigation systems. Rice cultivation by humans has had a significant impact on zebrafish habitat. ![]() Because of monsoon season in their native geographic range, zebrafish have adapted to a broad range of temperatures, from 6 degrees C during winter to 38 degrees C in summer. They are most often found in shallow, slow-moving water near the edge of streams or in ditches. Zebrafish live in freshwater streams and rivers but are more often considered floodplain species. A few introduced populations of the species inhabit inland waters in the United States (California, Connecticut, Florida and New Mexico) and Columbia, South America. Its has a broad geographic range in the Indian subcontinent, ranging from the Ganges and Brahmaputra river basins of Bangladesh, India, and Nepal. Danio rerio is native to inland streams and rivers of India. ![]()
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