Zebrafish
Introduction
The Zebrafish (Danio rerio) is a tropical freshwater fish belonging to the minnow family of the order Cypriniformes. Native to South Asia, it is a popular aquarium fish, frequently sold under the trade name zebra danio.
Anatomy and Morphology
Zebrafish are characterized by horizontal stripes that run along the length of their bodies, giving them their common name. Adult zebrafish typically grow to lengths of 4–5 cm, with males usually being slightly smaller and more slender than females. The body of the zebrafish is fusiform and laterally compressed, with its mouth directed upwards.
Habitat and Distribution
Zebrafish are native to the streams of the southeastern Himalayan region. They inhabit streams, canals, ditches, ponds, and slow-moving or stagnant water bodies, including rice fields. Zebrafish prefer water with a 6.0–8.0 pH, a water hardness of 5–19 dGH, and a temperature range of 20–26 °C (68–79 °F).
Life Cycle and Reproduction
Zebrafish are oviparous, and females can produce hundreds of eggs in each clutch. Upon fertilization, embryonic development occurs, and within 3–4 days, the larvae are free swimming. Zebrafish reach sexual maturity at approximately 10 weeks of age.
Genetics and Genomics
The zebrafish is a key model organism in scientific research, particularly in the fields of developmental biology and genetics. Its genome has been fully sequenced, revealing that it shares 70% of genes with humans. This genetic similarity, combined with the zebrafish's rapid reproductive cycle and transparent embryos, make it an invaluable tool in the study of vertebrate development and disease.
Use in Research
Zebrafish are used in research due to their regenerative abilities. They can regenerate their heart, spinal cord, retina, and fins. This makes them useful for studies on healing and tissue regeneration. In addition, their use in genetic manipulation has allowed for advancements in our understanding of cancer and other diseases.
Conservation Status
While zebrafish are not currently considered a threatened species, their habitats in South Asia are under pressure from human activities such as deforestation and pollution. Conservation efforts are focused on preserving their natural habitats and preventing further population decline.