Alaska Department of Fish and Game and Alaska 4-H

Alevin stage is exciting, but fish are fragile

In many instances the alevin stage is the most exciting and intriguing phase of early salmonid development that students witness. The egg, which has laid relatively motionless in the basket or gravel for months, finally hatches and a new stage of the salmonid is born. This newly hatched fish is called an “alevin.” Unfortunately, the excitement is sometimes short lived as alevins are genetically programmed to burrow into the gravel to escape light and predators. It is in the substrate where the alevin grow as they consume their yolk sac. Alevins are extremely delicate and should not be disturbed or removed from the tank as there is a high risk of rupturing the yolk sac. If alevin become difficult to observe, it is possible to gently lift gravel or substrate off the bottom to find pockets of these elusive fish, but be careful when replacing the moved material! Placing clusters of gravel throughout the tank instead of a solid layer of gravel will increase alevin visibility. If these awkward swimmers are seen swimming in the water column, remove the lid slightly to allow light to enter. This will stimulate the alevin to move back into their appropriate habitat. The more energy that is used from the stored yolk for swimming means that there is less available for growth. Swimming alevin may indicate problems with water quality, temperature, or fish health.
~Jay Baumer, Fisheries Biologist, Alaska Department of Fish and Game

ALEVIN Require

• Cool, clean, clear, dechlorinated water.
• Water temperatures that do not exceed 12°C.
• Dissolved oxygen levels of at least 10 mg/l (ppm).
• Water circulation for Oxygen-rich water through and around eggs.
• Little or no exposure to sunlight or artificial light.
• Sustainable substrate for cover and support.
​• Do Not Handle!

Power outages 

It is not uncommon over winter break to have power outages or have the chiller or filter become unplugged.  The best way to avoid this is to have a designated fish captain check on your tank frequently.

Log your Salmon ATu's

Please do not forget to keep track of ATU’s
You can estimate the temperature on weekends or over holiday breaks.
More information about temperature and salmon development available by contacting Alaska Dept. of Fish and Game:
http://www.adfg.alaska.gov/index.cfm?adfg=viewing.salmontemperature

Change water after hatching

Hatching eggs are very exciting.  The process; however, leaves a lot of egg bits floating in the water and may clog your filter.  Change the water, a bit at a time, with fresh water that does not contain bleach or other chemicals.

Photos from Salmon Scientists!
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