Professional Instructions for Hatching Brine Shrimp
Achieving a high hatch rate with Artemia cysts depends entirely on precision. Whether you are using a commercial 2-litre hatching cone, a laboratory Imhoff cone, or a DIY inverted soft drink bottle, this guide outlines the optimal conditions required to maximize your yield.
Correct Storage of Brine Shrimp Cysts
Before you begin hatching, you must start with viable, properly stored embryos. Exposure to moisture and the harsh Australian summer heat will rapidly degrade hatch rates.
- Airtight Seal: Always store cysts in a tightly sealed container completely free from moisture.
- Short-Term Storage (Under 4 Weeks): Keep the container in the refrigerator at or below 4°C.
- Long-Term Storage (4+ Weeks): Keep the container sealed in the freezer.
Important Note: Freezing lowers metabolic activity and can cause a slight delay in initial hatch-out times. We highly recommend removing your required portion of cysts from the freezer one day in advance to allow the embryos to acclimate to room temperature before hydration.
Optimal Environmental Conditions
For the highest hatch-out percentages in a conical or V-bottom vessel, maintain the following parameters precisely:
Salinity & Water Composition
A salinity of 25 parts per thousand (ppt) is optimal, which equates to a specific gravity of 1.018 on a standard hydrometer.
- The Manual Formula: If you do not have a hydrometer, dissolve 1 and 2/3 tablespoons of non-iodised salt (such as pure solar salt, pool salt, or marine salt) per 1 litre of water. Do not use iodised table salt.
pH Buffering
Artemia embryos require an alkaline environment to successfully break through their shells. A starting pH of 8.0 or higher is recommended. If your local tap water supply is soft or has a pH below 7.0, add magnesium sulphate (Epsom salts) or sodium bicarbonate at a rate of 1/2 teaspoon per litre of hatching solution to buffer it upward.
Temperature Control
The ideal water temperature for a complete 24-hour hatch is 26°C to 28°C.
- Lower temperatures will significantly prolong the incubation period (stretching it to 36+ hours) and decrease overall efficiency.
- Do not exceed 30°C.
- Safety Warning: Never place an aquarium immersion heater directly inside a small hatching cone, as it can create localized hotspots that cook the eggs. Instead, use an ambient water bath system or suspend an incandescent bulb directly above the cone.
Constant Aeration & Oxygenation
Continuous, vigorous aeration is required to keep the cysts in constant suspension and maintain a dissolved oxygen level above 3 parts per million (ppm).
- Use a rigid air tube pushed all the way to the absolute bottom apex of the cone to prevent unhatched eggs from settling out in dead zones.
- Do not use an airstone. Fine micro-bubbles cause excessive foam accumulation at the surface, which strands buoyant eggs high and dry on the walls of the vessel above the waterline.
Stocking Density
Maintain a density of 1 gram of cysts per 1 litre of water (approximately 1/2 a level teaspoon per litre). Exceeding this density reduces oxygen availability per cyst, lowers the total hatch percentage, and makes it incredibly difficult to cleanly separate the hatched nauplii from waste shells during harvest.
Step-by-Step Hatching & Harvesting Process
- Assemble and Fill the Vessel: Preparation.
Position a semi-translucent hatching cone in a well-lit area. Fill with water and mix your non-iodised salt to hit 25 ppt. Verify the temperature is stabilized between 26°C and 28°C. - Introduce Cysts and Aerate: Incubation.
Add cysts at 1 gram per litre and introduce a rigid air tube to drive heavy bubbling. Helpful Hint: Brine shrimp eggs are highly buoyant. Swirl the water with your finger once or twice during the first 4 to 6 hours to knock down any eggs stranded on the dry sides of the cone. After 6 hours of hydration, they will stay fully suspended in the water column. - Separate the Hatch: Settling.
After 18 to 24 hours (or up to 36 hours for older eggs), turn off the aeration completely. Let the cone sit undisturbed for 5 to 10 minutes. The empty, brown egg shells will float to the surface, while the unhatched cysts will sink to the very bottom apex. The newly hatched, orange baby brine shrimp (nauplii) will concentrate in a dense cloud just above the bottom apex, drawn toward light. - Siphon and Rinse the Nauplii: Extraction.
Gently siphon the orange cloud of nauplii using an airline tube (or drain through a bottom valve if your cone is equipped with one) into a fine-mesh sieve or brine shrimp net. Avoid letting them sit packed tightly at the bottom for too long, or they will quickly suffocate. Rinse the collected nauplii thoroughly with clean freshwater or fresh saltwater to flush away metabolic waste and prevent localized bacterial blooms in your display aquariums.
Determining Your Target Growth Stage
Depending on the size of the mouths of the fish fry or invertebrates you are feeding, you can target two distinct harvest windows:
- Instar I (First Stage Nauplii): Harvested early at approximately the 18-hour mark. These newly emerged larvae are at their absolute smallest size, making them perfect for tiny, sensitive fry (like newly born seahorses or larval crustaceans). At this stage, they still possess their highly nutritious yolk sacs.
- Instar II (Second Stage Nauplii): Harvested at 24 to 36 hours. At this point, the shrimp undergo their first molt, developing a functional digestive tract. While slightly larger, their direct nutritional value begins to decrease unless you actively enrich them using a specialized fatty acid formula (such as SELCO or microalgae pastes) prior to feeding.
Sanitisation Tip: Between every single batch, thoroughly wash down your hatching cones using a light chlorine or sodium hypochlorite solution, rinse exhaustively, and allow to air-dry completely. Avoid using dish soaps or domestic detergents. Soap leaves behind an invisible chemical residue that causes extreme foaming once heavy aeration is turned back on, rendering your next batch of cysts useless.
