The emerging of rainbow trout can take a few seconds to a couple of minutes. Temperature of the water and the amount of light, oxygen level can be also a potential factor. The size, shape and color can also be different from trout to trout. The emerged "fish" is called fry or alevin and at this stage they can't take solid food, they feed from their egg sack. It's content is rich in proteins and oils. After emerging the alevin doesn't show much movement for a couple of days.