Alevin

                                         An alevin is a newly hatched salmon or trout that still has its yolk-sac attached. The yolk-sac provides the alevin nourishment for the first 2-3 weeks after hatching. Typically, at this life stage, salmon or trout will stay in the gravel but they might be pushed into open water by a strong current, making them more susceptible to predation.(fishionary.fisheries.org/alevin)

An alevin with a orange yolk-sac attached (photo credit: fishbio.com)