Hatching Brine Shrimp (Artemia) for Fish and Fry
How aquarists hatch Artemia cysts into nauplii as a live first food for fry and small fish, covering salinity, temperature, hatch time, aeration, harvesting and feeding promptly.
Overview
Brine shrimp (Artemia) are small crustaceans whose newly hatched larvae, called nauplii, are one of the most widely used live first foods for fish fry and small fishes in both aquaculture and the aquarium hobby. Artemia produce dormant cysts (often sold as eggs) that can be stored dry and hatched on demand, making them a convenient, nutritious live food.
Equipment
A simple hatchery is a clear cone or an inverted bottle that allows strong aeration from the bottom so the cysts stay in constant motion. An air pump and airline supply the aeration, and a light placed near the hatchery improves hatch rate and later helps harvest the nauplii, which are attracted to light.
Hatching conditions
| Parameter | Typical range | Note |
|---|---|---|
| Salinity | About 25 g/L (roughly 25 ppt) salt water | Artemia tolerate a wide range; hatching is done in salt water |
| Temperature | About 25 to 28 deg C | ~28 deg C is commonly cited as optimal for hatching |
| Hatch time | About 18 to 36 hours | Warmer water hatches faster |
| Aeration | Strong, continuous | Keeps cysts suspended and oxygenated |
| Light | Continuous / strong | Improves hatch and helps harvesting |
Cysts are added to aerated salt water; a small amount of sodium bicarbonate can be used to buffer the pH if it is low. Under good conditions a high proportion of cysts hatch within roughly a day; controlled studies report optimal hatching around 19 hours at about 29 deg C and 28 ppt salinity.
Harvesting
When hatching is complete, turn off the aeration and let the contents settle for a few minutes: the empty shells float to the top, unhatched cysts sink, and the orange nauplii gather in the middle, where they can be drawn off. Shining a light at one side helps concentrate the nauplii. Collect them in a fine net or sieve and rinse them in fresh water before feeding, to remove salt and debris.
Feeding and enrichment
Feed nauplii promptly after hatching. The freshly hatched, first-stage (instar I) nauplii still carry their yolk reserve and are the most nutritious; as they swim and feed, the yolk depletes and their food value drops, so they are best used soon after hatching. For larger fry, older nauplii can be enriched with suitable feeds to boost nutritional value.
Decapsulation (optional)
Some hobbyists decapsulate cysts before hatching, removing the hard outer shell with a measured bleach (hypochlorite) treatment after hydration. Decapsulation removes shell debris (so it need not be separated from the nauplii) and can improve hatch energy, but it requires careful handling of the chemicals and thorough rinsing.