After the eggs hatch (the alevin stage), it takes about a week or two for the yolk sac to be absorbed. Once absorbed, this is the “button up” or swim-up stage and the salmonids will begin swimming to the surface of the water to search for food.
When to feed #
At the sign of swim-up stage, drop a few grans of fish over the basket and see if the trout swim up. A great rule of thumb for all stages of life in the tank is to only feed fish as much as they can consume in one minute!
Not all fish will develop at the same rate; you will still have alevin at the bottom of your breeder basket while others are swimming up. If some are much more delayed than others, you can release stronger trout into the larger aquarium and keep the less developed trout in the breeder basket until they are swimming up and feeding.
What does swim-up look like? #
This video from PA Fish & Boat has great visuals of this stage and can help identify what to look for in this stage of the trout life cycle.