Alevins are the stage in which the eggs hatch out into tiny embryonic fish that still have their yolk sac attached. At this stage of their life they are still amongst the gravel redd. The term "Redd" is a bed of loose gravel that fish use to spawn. The female digs a trench or pit in the gravel, usually with her body and tail, she then lays her eggs. At this critical stage the male trout releases sperm over the eggs and the eggs are then covered over with gravel.

When the alevins yolk sac is used up of it's nutrients they then turn into proper fry. After this stage they come up through the gravel and start to feed.

It isn't long before the fry grow and quickly they look more like a trout. They develop marks down their sides called Parr marks. This is when they are now called "Parr". Depending on the amount of food available to the fish, they can stay as parr from 1 - 4 years until they become adult trout. At this stage any sea going and Lough varieties of trout head down stream eventually into the sea or Lough while the river trout start developing there adult coloration.

Trout can come into breeding condition from the age of 3 years upwards. They then make their way to the spawning sites.

Sea trout and a lot of lake types of trout like our Dollaghan trout tend to feed in shoals and then tend to run the river in loose shoals as they make their way towards the gravel breeding grounds. They tend not to eat or eat very little while they are in the river during the spawning stage.
In contrast, the river trout, which are solitary feeders, remain solitary as they move to the spawning grounds.