Hatching Brine Shrimp

How to Test for Nauplii Per Gram (NPG) and Hatch Brine Shrimp to use as feed.

 Materials required

  • Imhoff/Nalgene transparent cone (1000 ml / 1 L)
  • 25 grams table salt
  • NaHCO3 (Baking Soda)
  • 2000 lux of light
  • Brine Shrimp (1 gram)
  • Air supply
  • Heater
Hatching Brine Shrimp

Hatching Brine Shrimp

1. Prepare saline solution by dissolving 25 grams of salt in an Imhoff transparent cone of 1 liter or 1000 ml of water (25 grams of salt is equal to about one heaping table spoon). Add a pinch of baking soda as a buffer.  A pH of 8.0-8.5 is optimal and the baking soda should take care of this.

2. Test cones must have aeration from the bottom at all times (constantly agitating the cysts), as well as being illuminated by lights (2000 lux) during the full 24 hr. incubation process.

3. A temperature of 25°-29° Celsius must be present and consistent during the full 24 hr. incubation. Temperatures below 25º Celsius will need more than 24 hours to get the guaranteed hatch rate. Temperatures above 30º Celsius will stop the cyst from completely hatching, and is irreversible.

4. Exactly 1.00 gram of Artemia Cysts is measured out for testing. If hatching the cysts for harvesting, do not exceed 2 grams of cysts per liter of saline solution. If the density exceeds this the cysts will not achieve their optimal hatch-out.

5. Add Artemia Cysts to the saline solution to incubate for 24 hours.

6. Occasionally the sides should be washed down with saline solution to keep eggs from drying on the side. This is usually only needed at the beginning until the cysts become hydrated. However lower grade cysts will tend to stick more than higher grade cysts. (*If harvesting Artemia for feed please skip to the asterisk at the bottom.)

7. After 24 hours, with aeration and illumination still on, draw exactly 1 ml with a pipette of the saline/artemia solution.

8. Evenly spread the 1ml sample across filter paper and count the only the fully hatched nauplii.

9. Take the number counted and multiply this by 1000 to arrive to at the NPG (nauplii per gram) count (i.e. 235 nauplii * 1000 = 235,000 NPG.) To find the Hatching percentage take the NPG and divide it by 275,000 cysts per gram (CPG). 235,000/275,000=85%

10. When finished counting, turn off aeration, let cysts and nauplii separate for about 10 minutes…the cysts shell will float while the nauplii (baby brine shrimp) will settle to the bottom of container. Separation is graded by the following criteria:

Separation of Nauplii from Cyst

Separation of Nauplii from Cyst

  • the eggs is “GREAT” if their is no egg stuck the side of the cone inside the water column, all the shell floats to the top, the nauplii sink to the bottom, and the nauplii are a bright orange color.
  • the egg is “GOOD” if the nauplii color is a dull orange, OR the cone contains a SMALL amount of egg stuck to the side, OR a VERY SMALL amount of cysts shells settle at the bottom with the nauplii.
  • the egg is “FAIR” if there is a MODERATE amount of cysts shell in the nauplii, or if there is a fair amount of egg stuck on the side of the cone.
  • the egg is “POOR” if there is a lot of cysts shells in the nauplii, the water is cloudy, or the whole cone is just poor looking or may have bacteria contamination.


  • Note:  Switch off the aeration after 24 hours.  Let stand for 5-10 minutes.  Nauplii (young brine shrimp) will settle at the bottom of the container while their shells will float.  Siphon or drain nauplii into a fine mesh net.  Rinse with clean fresh water.  The shrimp are now ready to be used as feed.


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