Zebrafish Feeding Guide: Live vs. Dry Food

What Does Zebrafish Eat? Balancing Nutrition and Convenience with Live and Dry Food

Feeding zebrafish a balanced diet is a cornerstone of effective husbandry. Zebrafish can thrive on both live and dry food, each with distinct benefits and applications depending on the fish’s age, size, and nutritional needs. This guide explores the differences between live and dry food, how to use them effectively, and tips for maintaining an optimal feeding regimen.

1. Understanding Zebrafish Feeding Needs

Zebrafish are omnivorous and require a diet that provides essential nutrients for growth, health, and reproduction. Feeding strategies differ for larvae, juveniles, and adults:

• Larvae: Require smaller, high-protein food to support rapid growth.
• Juveniles and Adults: Transition to larger food sizes with balanced protein, fat, and carbohydrates.
• Breeding Adults: Benefit from live food to enhance reproductive health.

2. Dry Food: Convenience and Scalability

Dry food, such as pelleted or powdered feed, is a staple in zebrafish husbandry due to its convenience and consistent nutritional profile.

• Sizes of Dry Food:
  • <100 microns: Powdered food for newly hatched larvae.
  • 100–200 microns: Ideal for slightly older larvae as they grow.
  • 200–400 microns: Suitable for juveniles.
  • 400–600 microns: Standard size for adult zebrafish.
• Feeding Schedules:
  • Larvae: 3 times daily using powdered food, with quantities adjusted to avoid waste.
  • Adults: Twice daily (morning and evening) using small measured scoops (e.g., 1/16 teaspoon).
• Advantages of Dry Food:
  • Long shelf life and easy storage.
  • Consistent nutritional composition.
  • Scalable for large colonies.

3. Live Food: Nutritional Density and Enrichment

Live food offers superior nutritional value and supports natural feeding behaviors in zebrafish. Commonly used live foods include:

• Rotifers:
  • Nutritionally dense (protein ~40%; lipid ~10%) and easy to culture.
  • Ideal for feeding larvae and enhancing the breeding potential of adults.
  • Rotifers are harvested daily and fed fresh to zebrafish.
• Paramecia:
  • Small and easy for larvae to consume.
  • Often used for the youngest stages of zebrafish development.
• Artemia (Brine Shrimp):
  • High in protein (~50%) and lipids (~15%).
  • Excellent for juveniles and breeding adults.

Benefits of Live Food:

• Promotes better digestion and absorption of nutrients.
• Stimulates natural hunting behavior.
• Improves breeding performance in adults.

4. Culturing Rotifers Setup: Live Food Maintenance

Rotifers are a popular choice for zebrafish facilities due to their nutritional density and ease of cultivation. Rotifers are grown in two main ways:

1. A continuous culture: harvesting 10-20% of one big culture each day
2. Batch culture: harvesting 100% of a smaller culture, multiple cultures growing at the same time.

Rotifers may be particularly sensitive to any changes in their environment such as the amount of food, consistency of aeration, etc., so it is ideal to have multiple cultures in case of a colony decline. 

• Setup for Rotifer Culture:
  • Use 5-gallon buckets equipped with air stones for aeration.
  • Maintain algae stock in a fridge at 4°C and pump it into the buckets periodically.
  • Filter floss catches debris and minimizes ammonia buildup.
• Daily Maintenance:
  • Perform water changes of 20–50% to control ammonia levels.
  • Replace filter floss daily to keep debris under control.
• Harvesting Rotifers:
  • Pass bucket contents through a 120-micron filter to remove debris and a 50-micron filter to collect rotifers.
  • Rinse rotifers with 5 ppt (parts per thousand) saltwater to prepare them for feeding.
• Feeding Rotifers to Zebrafish:
  • Freshly harvested rotifers can be stored on a benchtop with an air stone and algae for short-term use.
  • Add them to larval or adult tanks as needed throughout the day.

Rotifers are typically shipped live, meaning that any colony decline will require another live shipment.

5. Culturing Artemia Setup: Live Food Maintenance

Artemia is another excellent live food option for zebrafish facilities due to its ease of storage and high nutritional value. Unlike rotifers, Artemia can be stored as cysts and hatched on demand, making it a reliable choice when maintaining a consistent food supply. This ensures a consistent supply without the risk of shipping delays. Below are the steps for culturing Artemia in a zebrafish facility:

• Setup for Artemia Culture:
  • Cysts Storage: Keep Artemia cysts in an airtight container in the freezer.
  • Hatching Vessel: Use conical containers or buckets with air stones for aeration. Maintain salinity at 25–35 ppt.
  • Light and Temperature: Provide bright light (2,000 lux) and maintain 25–28°C for optimal hatching.
• Hatching Artemia:
  • Incubation: Hydrate cysts in dechlorinated water for 1–2 hours, then aerate for 24 hours until nauplii hatch.
  • Harvesting: Stop aeration, let cysts settle, and filter nauplii with a 120–150-micron mesh. Rinse with fresh water.
  • Decapsulation (Recommended): Prevents intestinal blockages in fry, reduces health risks, and improves juvenile survival rates.
    • Hydrate the cysts.
    • Dissolve the chorion using NaOH and ClO⁻.
    • Neutralize the solution with HCl and rinse thoroughly.
• Feeding Zebrafish:
  • Short-Term Storage: Keep nauplii aerated on a benchtop for up to 24 hours.
  • Feeding: Add freshly hatched nauplii to tanks as needed, adjusting for population size.
• Daily Maintenance:
  • Clean hatching vessels after use.
  • Inspect cyst stocks regularly for dryness and viability.

This process provides a consistent, high-quality food source for zebrafish with minimal effort.

6. Live vs. Dry Food: Choosing the Right Option

While both live and dry food are essential in zebrafish husbandry, choosing the right option depends on the specific requirements of your colony:

6. Best Practices for Zebrafish Feeding

To ensure optimal health and growth:

• Combine Feeding Types: Use a mix of live and dry food to balance convenience with nutrition.
• Avoid Overfeeding: Only provide as much food as the fish can consume in a few minutes to reduce waste and maintain water quality.
• Observe Feeding Behavior: Ensure all fish have access to food, particularly in densely stocked tanks.

Conclusion

Feeding zebrafish the right diet is critical for their health and the success of research outcomes. A combination of live and dry food offers the best of both worlds: the convenience and consistency of dry food, paired with the nutritional and behavioral benefits of live food. By tailoring feeding strategies to the needs of your zebrafish, you can ensure a thriving and productive colony.

By Miriam Martinez

Miriam is a Human Biologist with a strong background in neuropharmacology and a passion for bridging science and innovation. After earning a master’s degree in the Pharmaceutical and Biotech Industry, she completed her PhD in Biomedicine at Pompeu Fabra University (Barcelona), where her research focused on the behavioral analysis of animal models for neurophenotypical characterization. Following her doctoral studies, Miriam transitioned into the healthcare marketing and communication sector, where she played a key role in developing impactful marketing strategies and educational campaigns for leading pharmaceutical brands. She now leverages her scientific expertise, strategic thinking, and creative communication skills in her current role at ZeClinics.