Brine shrimp, scientifically known as Artemia, are small crustaceans widely utilized in aquaculture and the aquarium trade as a live feeder organism. These creatures possess a remarkable ability to thrive in hypersaline environments, such as salt lakes and solar salt works. Their unique life cycle, which includes a dormant cyst stage, makes them convenient for storage and on-demand hatching. Understanding the specific dietary requirements of brine shrimp is essential for successfully raising them from their larval stage, or nauplii, through to adulthood.
Natural Diet and Filter Feeding
Brine shrimp are non-selective filter feeders, consuming microscopic particles suspended in the water column. Their diet primarily consists of phytoplankton, bacteria, and organic detritus. In their natural, highly saline habitats, food sources often include halophilic organisms and microalgae, such as those from the genus Dunaliella.
The process of feeding involves the rhythmic beating of leaf-like appendages, called phyllopodia. These appendages generate a current that draws water and food particles toward the midline of the body. Fine bristles on the limbs filter the particles, which are then transferred to a central food groove and moved forward to the mouth. This filter-feeding system allows them to continuously graze on particulate matter, typically ingesting anything smaller than 50 micrometers (µm).
Feeding Newly Hatched Nauplii
The life stage immediately following hatching is the nauplius, which has distinct nutritional requirements. The newly hatched larva (instar I) does not feed for the first eight hours, subsisting entirely on its yolk reserves. Once it molts into the instar II stage, the nauplius must begin consuming external food particles to survive and grow.
The digestive tract of the nauplius requires food particles to be exceptionally small, ideally ranging from 1 to 50 µm, with a preference for sizes around 3 to 8 µm in the first week. Appropriate starter foods include commercial liquid fry foods or atomized phytoplankton, which keeps the tiny particles in suspension. Baker’s yeast can also be used, but it requires careful preparation and dosage to prevent fouling the water, as the particles must be finely dispersed for the nauplii to ingest them.
Sustaining Adult Cultures
As brine shrimp grow from nauplii into juveniles and adults, their filtration capacity increases, allowing them to tolerate a larger particle size. They can efficiently consume particles up to approximately 50 µm. For maintaining established colonies, common food sources include powdered spirulina, which is a protein-rich micro-alga, or commercial growth formulas.
When raising brine shrimp for use as a feeder organism, their nutritional quality is directly linked to the diet they are provided, a process often called bio-encapsulation or enrichment. Newly hatched nauplii are deficient in certain Highly Unsaturated Fatty Acids (HUFA), such as Docosahexaenoic Acid (DHA), which are essential for marine fish and shrimp larvae. Therefore, adult cultures are often fed foods rich in HUFA, like specialized enrichment emulsions or concentrated algae pastes, to enhance their nutritional profile before being fed to other aquatic life. Monitoring the water’s turbidity ensures the animals are adequately fed without overfeeding, which can quickly degrade water quality.