Life cycle of the Tasmanian rainbow trout:
Trout eggs have black eyes and a central line that show healthy development. Egg hatching depends on the water temperature in an aquarium or in a natural habitat.
Once hatched, the trout have a large yolk sac used as a food source. Each alevin slowly begins to develop adult trout characteristics. An alevin lives close to the gravel until it “buttons up.”
Buttoning-up occurs when alevin absorb the yolk sac and begin to feed on aquatic insects. Fry swim close to the water surface, allowing the swim bladder to fill with air and help the fry float through water.
4. Fingerling and parr
When a fry grows to 2-5 inches, it becomes a fingerling. When it develops large dark markings, it then becomes a parr. Many schools that participate in the Trout in the Classroom program in Nevada will release the Tasmanian rainbow trout into its natural habitat at the fingerling stage.
In the natural habitat, a trout avoids predators, including wading birds and larger fish, by hiding in underwater roots and brush. As a juvenile, a trout resembles an adult but is not yet old or large enough to spawn.
In the adult stage, female and male Tasmanian rainbow spawn in autumn. Trout turn vibrant in color during spawning and then lay eggs in fish nests, or redds, in the gravel. The life cycle of the trout continues into the egg stage again.