Zebrafish Larva
Danio rerio
Type: freshwater
Physical Characteristics
Translucent body, large dark eye, visible yolk sac in early stages, elongated form with a developing dorsal fin and long tail. It lacks the horizontal adult stripes at this stage.
Habitat & Distribution
Native to the Ganges and Brahmaputra river basins in India, Pakistan, Bangladesh, and Nepal; often found in rice paddies and slow-moving streams.
Size & Weight
As larvae, they are typically 3-4 mm in length. Adults reach about 3-5 cm.
Similar Looking Species
Other Danio species larvae, though the Zebrafish is the specific model organism most common in research settings like the one pictured.
Ecological Role
In the wild, they serve as a food source for larger fish and help control populations of small invertebrates.
Diet
Larvae consume microzooplankton such as rotifers and paramecia. Adults are omnivores.
Behavior
Larvae exhibit rapid escape responses (C-starts) and become active swimmers within days after hatching. Adults are highly social and school.
Reproduction
They are high-fecundity spawners; a female can lay hundreds of eggs which hatch in about 48-72 hours depending on temperature.
Conservation Status
Least Concern (IUCN)
Identification Tips
Look for the large eye relative to the head size and the very clear, translucent body typical of early developmental stages.
Interesting Facts
Zebrafish are crucial in scientific research because they share 70% of their genes with humans and their embryos are transparent, allowing scientists to watch organs develop in real time.
Identified on: 5/20/2026
Mode: Standard