Brine shrimp, also known as Artemia, are a popular live food source in the aquarium hobby, prized for their ability to trigger a strong feeding response in fish. While convenient artificial diets exist, the lively movement of brine shrimp is often more enticing to fish.
The Appeal of Live Brine Shrimp
The benefits of feeding live Artemia are well-recognized within the aquarium community. Although many commercially available artificial diets aim to eliminate the need for live food, these inert alternatives often fail to elicit the same enthusiastic feeding response as live brine shrimp. The jerky, erratic swimming of live brine shrimp is irresistible to many fish species. Brine shrimp exhibit rapid growth, increasing in weight 500-fold within three to four weeks, and reaching a size of 1.5 centimeters from an initial 450 microns.
Culturing Brine Shrimp: Challenges and Considerations
Raising brine shrimp to maturity in substantial quantities can be a labor-intensive process, potentially demanding as much time and effort as breeding and caring for baby fish. Success is not always guaranteed.
Culture Tank Design
Assuming successful hatching, culturing brine shrimp requires careful attention to several design considerations for the culture tank:
- Temperature Control: Maintaining a stable temperature is crucial for optimal growth.
- Adequate Aeration: Sufficient aeration ensures adequate dissolved oxygen levels and keeps food particles suspended in the water column. Small bubbles are more effective for oxygen transfer, but very fine bubbles can interfere with feeding.
- Water Filtration: Implementing internal or external water filtration, or partial water replacement, helps maintain water quality.
- Detritus Removal: Effective removal of detritus, mortalities, and fecal matter is necessary through screened drainpipes or siphoning.
Culture systems range from simple batch systems to sophisticated flow-through tanks designed for high-density culture.
Read also: Pistol Shrimp Dietary Needs
Estimating Brine Shrimp Population
Counting minuscule baby brine shrimp can be challenging. The easiest method involves sampling from a randomly distributed population. Small aliquots are extracted, counted, and the results are extrapolated to estimate the total population.
For example, starting with one gram (approximately 1/2 teaspoon) of eggs with an 80% hatch rate, the following steps can be taken:
- Transfer the hatched brine shrimp to a one-liter bottle containing clean seawater with aeration.
- Use a one-milliliter pipette to extract a sample.
- If the sampling technique is accurate, each milliliter should contain approximately 200 animals.
If this process seems too tedious, consider enriching the newly hatched brine shrimp with supplements like SELCO and feeding them directly to the fish.
Water Quality Parameters
- Salinity: The optimal salinity range for culturing brine shrimp is 35-40 ppt (specific gravity 1.024-1.028). Unlike hatching solutions where household salts can be used, culture water should be prepared with aquarium-grade marine salt.
- pH: The initial pH should be between 7.5 and 8. pH tends to decrease during the culture period and can be adjusted with baking soda (NaHCO3).
- Dissolved Oxygen: Artemia are generally tolerant of low dissolved oxygen levels. However, oxygen stress can be indicated by a reddening of the animals. Ensuring adequate aeration usually prevents dissolved oxygen issues.
- Temperature: Maintain a temperature between 20°C and 25°C (68°F-79°F).
Brine Shrimp Nutrition
Artemia are continuous, non-selective filter feeders. The primary challenge in culturing them lies in providing appropriately sized feed in sufficient concentrations without compromising water quality.
Feeding Strategies
Tank design and aeration play a crucial role in distributing feed evenly throughout the water column. Feed must remain suspended to be accessible to the brine shrimp, achieved through directional airlifts, air stones, and return water flows.
Read also: A Guide to Peacock Mantis Shrimp
Water Quality Management
Nitrogen levels need monitoring. Regular removal of suspended solids, uneaten food, fecal matter, and detritus is essential for maintaining adequate water quality. This poses a challenge: efficiently removing pollutants without removing food.
The approaches to filtration are often more intuitive than strictly scientific. Some loss of food density during filtration is unavoidable. Filters with progressively larger mesh sizes can be used as the animals grow. Starting with a 100-micron filter, the mesh size can be increased to 350 microns when the brine shrimp are about two weeks old. Regular filter cleaning is essential, and placing air stones in front of effluent filters helps prevent clogging.
Monitoring Culture Health
Regularly examine a water sample in a beaker against a light source to assess culture density, food cell density, and animal health. Observing the fullness of the gut can indicate whether the animals are adequately fed. Food cell density can also be measured using a Secchi disc to assess water clarity.
Optimal Food Sources
The preferred food for Artemia is cultured, live diatoms, including species like Nannochloropsis sp., Tetraselmis sp., and Dunaliella sp. However, providing live diatoms requires a separate culturing effort. Brine shrimp are continuous feeders and can quickly deplete the water of diatoms at high densities.
Readily available alternatives include cryo-preserved algae pastes, particularly Nannochloropsis sp. or proprietary mixes like Tahitian Blend, which contains multiple algae species and stabilized vitamin C. These non-viable, highly concentrated algal cells can be added to the culture tank drop-wise.
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Other successful feeds include spray-dried, single-celled yeasts, such as Torula, and micronized forms of rice bran, corn bran, and soybean. These are often used in combination with other feed sources. Particle sizing can be achieved by micronizing brans with seawater and filtering through a fine mesh bag. Spray-dried Arthrospira platensis (formerly Spirulina platensis) can also be used.
Dunaliella veridis is a microscopic algae that can keep brine shrimp healthy.
Culture Systems
Various systems exist for growing brine shrimp. High-density culture (10,000+ animals per liter) requires robust mechanical filtration and water exchange, effectively a raceway system with ancillary treatment and filtration equipment. Lower-density "batch" systems (1,000 animals/lt.) rely on regular water exchange or dilution with clean seawater and detritus removal. Batch systems often involve lower feeding rates, resulting in slower growth.
Potential Problems
Filamentous Leucothrix bacteria can emerge in the protein-rich culture environment. Vibrio sp. bacteria and other infectious diseases may also occur. These outbreaks can be treated with antibiotics or controlled by increasing salinity.
Brine Shrimp as Fish Food
Nutritional Value
Live baby brine shrimp (Artemia nauplii) are a popular and essential food source for many aquarium fish species. They are high in protein and fatty acids, including omega-3 and omega-6, which are vital for fish health and development. Their small size makes them ideal for small and newly hatched fish.
Gut Loading
Adult brine shrimp can be "gut loaded" by feeding them nutritious foods like spirulina, vitamins, or even medications. This enhances their nutritional value and allows them to deliver medications to fish. Brine shrimp are indiscriminate filter feeders, consuming particles smaller than 50 microns.
Fresh vs. Frozen
While frozen brine shrimp is a convenient option, freshly hatched brine shrimp offer superior nutritional value. Newly hatched brine shrimp have an oil-rich egg sac, providing essential nutrients. Freezing baby brine shrimp may diminish their nutritional value.
Brine Shrimp in a Balanced Diet
While brine shrimp can be a valuable component of a fish's diet, it is best to feed a variety of foods. Mysis shrimp are often considered more nutritious than brine shrimp. Some aquarists have successfully fattened up fish, such as Achilles tangs, on spirulina-enriched brine shrimp.