Do Brine Shrimp Eggs Float or Sink? A Guide to Hatching Brine Shrimp

Brine shrimp eggs also known as cysts or artemia salina eggs are a popular live food source for feeding fish and invertebrates. But when it comes to hatching brine shrimp, many aquarists wonder – do brine shrimp eggs float or sink?

The answer is it depends on the stage of development. Here’s a quick overview of what happens during the brine shrimp life cycle

• Dry brine shrimp eggs (cysts) initially float at the surface of saltwater when first added The eggs have an oil droplet inside that provides buoyancy

• Within a few hours, the cyst shells begin to soften and sink to the bottom. This is when the hatching process begins.

• After about 18-36 hours of incubation, the brine shrimp nauplii hatch out of the cysts and are free swimming. The baby brine shrimp nauplii are positively buoyant and float up in the water column.

Below we’ll go into more detail on brine shrimp eggs stages and tips for successfully hatching brine shrimp.

Stages of Brine Shrimp Eggs

Brine shrimp undergo an incredible metamorphosis during their life cycle. Here are the key stages:

Cyst Stage

• Cysts are the dehydrated brine shrimp eggs which can remain dormant for years.

• They initially float at the water’s surface due to an oil droplet inside that provides buoyancy.

• Cysts are brownish in color and about 200-300 microns in size.

• When viewed under a microscope, you can see the embryo of the brine shrimp tucked inside.

Activated Cysts Stage

• After 6-12 hours of being hydrated in saltwater, the outer shell of the cysts begin to soften and sink.

• The metabolism of the brine shrimp embryo speeds up as it starts to prepare for hatching.

• The cysts turn from brown to a lighter tan color during this activated stage.

Nauplii Stage

• After about 18-36 hours of incubation, the brine shrimp hatch out of their cyst shells as free swimming nauplii.

• The nauplii are positively buoyant and will float up in the water column.

• Newly hatched nauplii are around 400-500 microns in size.

• Nauplii molt and grow through several instar stages, becoming larger after each molt.

• After 5-8 molts over 2-3 weeks, they reach adulthood as adult brine shrimp.

Tips for Hatching Brine Shrimp Eggs

Follow these best practices for hatching healthy brine shrimp nauplii:

Use High Quality Cysts

• Look for cysts that are brown in color with no white spots which can indicate dead eggs.

• Avoid old eggs which have been stored too long and lose hatch rate.

• Refrigerate cysts for storage and use within 1-2 months for best hatch rates.

Optimal Hatching Conditions

• Use marine salt to create 25 ppt salinity saltwater.

• Maintain pH above 8.0. Add Epsom salt if needed to buffer pH.

• Keep temperature 82°F. Warmer temperatures speed up hatch time.

• Use strong aeration to keep cysts suspended.

• Provide lighting to trigger hatching response.

Rinse Well

• Rinse nauplii well to remove hatching debris and bacteria.

• Rinsing helps improve water quality for fish and invertebrates.

Harvest at Right Time

• For maximum nutrition, harvest brine shrimp nauplii within 24 hours before yolk sac is depleted.

• Or harvest at 18 hours for smaller Instar I nauplii for feeding fry.

What To Do If Brine Shrimp Eggs Are Not Hatching

Sometimes brine shrimp cysts can be stubborn and refuse to hatch. Here are some troubleshooting tips if your brine shrimp eggs are not hatching:

• Double check saltwater salinity is exactly 25 ppt. Being too high or low inhibits hatching.

• Test pH and make sure it’s 8.0-8.3. Low pH reduces hatch rates.

• Check water temp is 82°F. Colder temps will stall hatching.

• Use an airpump with strong aeration to keep cysts suspended.

• Add a light source to trigger hatching response if incubating in darkness.

• Try a new batch of eggs if old. Hatch rates drop over time in storage.

• Extend incubation time up to 48 hours if eggs are older.

• Consider disinfecting hatchery equipment if bacterial bloom present.

Be patient, dial in the optimal hatching conditions, and you should soon have a thriving batch of baby brine shrimp swimming around. They make an excellent starter food for fish fry and reef tank critters.

Harvesting Your Brine Shrimp Nauplii

Once your brine shrimp eggs have hatched, you’ll want to harvest the nauplii. Here are a few tips:

• Turn off the air pump and allow the nauplii to settle for 5-10 minutes. This allows them to separate from the floating cyst shells.

• Use an air line tubing as a siphon to suck up the nauplii from the bottom of the hatchery.

• Slowly drain the nauplii out through a valve if your hatchery cone has one.

• Gently scoop out the nauplii with a small fine mesh net. Avoid damaging them.

• Rinse the nauplii in clean saltwater before feeding them out.

Enriching Your Brine Shrimp

To boost the nutritional value of brine shrimp even further for your fish, you can enrich them. Here are some enrichment options:

• Add a seaweed solution like Kent Marine PhytoPlex. This will turn the nauplii green.

• Soak in a vitamin solution like Selcon for 6 hours prior to feeding.

• Feed the nauplii a nutritional dry food like azimuth Artemia Booster.

• Or even feed the adult brine shrimp an enrichment food before harvesting their eggs.

Enriching the brine shrimp helps provide essential fatty acids, vitamins, minerals and more to your fish. This is especially important for raising show quality fish.

Storing Extra Brine Shrimp Nauplii

Have some extra brine shrimp left over after feeding your fish? Here are some storage tips:

• For short term storage, keep brine shrimp refrigerated in clean saltwater and use within 2 days.

• For longer storage up to 2 weeks, freeze brine shrimp in ice cube trays with a bit of saltwater.

• When ready to use, defrost frozen brine shrimp by moving to refrigerator overnight or placing cube in tank to thaw.

• Previously frozen brine shrimp may take an hour or two to regain movement/color once defrosted before feeding out.

Proper storage is important to keep your freshly hatched brine shrimp nauplii viable for extended periods.