Stocking density regulations

For aquaponics systems in the EU, as of January 26, 2026, there are no uniform, EU-wide binding stocking density regulations for the fish species mentioned. The regulation is complex and based on several legal areas.

Here is an overview of the relevant regulations and principles:

1. The Overarching Principle: EU Animal Welfare Law

The fundamental legal source is the EU Animal Welfare Regulation (EC) No. 1099/2009 on the protection of animals at the time of killing, which also contains general principles for husbandry. The EU's "Farm to Fork" Strategy and the ongoing legislative process for revising animal welfare regulations stemming from it are crucial. Here, the trend clearly points towards species- and system-specific requirements (e.g., that fish must be able to exhibit their natural behavior). Generic kg/m³ figures are currently not set at the EU level.

2. The National Framework: German Animal Welfare Livestock Husbandry Ordinance (TierSchNutztV)

In Germany, as a key EU member state, the requirements of the TierSchNutztV (Annex 8 - Minimum requirements for the keeping of freshwater fish) are decisive. For most of your mentioned freshwater species (such as sturgeon, carp, tilapia, pangasius, trout, pike-perch), the following generic specifications apply:

• Minimum water volume per fish: Depending on final body weight (e.g., 50 liters per carp >750g, 100 liters per sturgeon >1,500g).
• Generic stocking density upper limit: Maximum of 15 kg of fish per 1,000 liters (1 m³) of utilized water volume (exception: trout up to 25 kg/m³ under specific conditions).
• Oxygen: >5 mg/l, measured at the tank outlet.
• This generic 15 kg/m³ limit has often been criticized as very conservative for modern recirculating aquaculture systems (RAS) and even more so for aquaponics systems.

Important Note: For some of your mentioned species, no specific requirements exist in the TierSchNutztV (e.g., African catfish, shrimp, Pacific pollock, cobia). Here, the general animal welfare paragraph (§ 2) applies, which demands "species-appropriate" husbandry.

3. The Special Case Aquaponics: Fertilizer and Wastewater Law

Since nutrients from fish farming are used as fertilizer for plants in aquaponics systems, fertilizer law is additionally relevant.

• The EU Fertilising Products Regulation (EU) 2019/1009 recognizes "nutrient recovery products," which legally facilitates the use of aquaponics effluent for plant production.
• At the national level (e.g., the German Fertiliser Ordinance - DüV), strict limits for nutrient application (nitrogen, phosphorus) apply. The stocking density must be chosen so that the resulting nutrient load can be completely taken up by the plant culture to prevent accumulation or unauthorized application. This is often the limiting factor for stocking density in aquaponics systems, not the volume alone.

4. Practice and Recommendations for Your Species (Status 2026)

For aquaponics systems, lower stocking densities are often chosen in practice today compared to pure fish production systems (RAS) to ensure system stability and balance the nutrient budget. Typical target ranges in established systems often lie between 10-40 kg/m³, heavily dependent on:

• Species: Saltwater species (sea bass, sea bream) or particularly stress-sensitive species (eel) often require lower densities.
• System Design: Performance of filters (biofilter, clarifier), oxygen input, plant component ratio.
• Management: Feed conversion ratio (FCR), water exchange rate.

Examples of common practical values in modern systems:

• Tilapia, African Catfish, Pangasius: Often 20-50 kg/m³ (in pure RAS up to 80 kg/m³+, in aquaponics usually lower).
• Trout, Pike-Perch, Sturgeon: Usually 15-35 kg/m³.
• Sea Bream, Sea Bass: 15-25 kg/m³.
• Carp: Often lower, 10-20 kg/m³, as they are bottom-oriented.
• Shrimp: Regulated by individuals/m² or /m³, e.g., 50-150/m² for Macrobrachium.

Conclusion and Recommendation for Action:

1. Legally binding are primarily the national animal welfare regulations (in Germany: TierSchNutztV, Annex 8) with their generic specifications (e.g., 15 kg/m³ for many species).
2. Aquaponics practice is guided by the nutrient budget for plant growth and system stability, which often leads to adjusted densities.
3. You must check the regulations of your respective EU member state. For new facilities, permits under national immission control law (e.g., the German Federal Immission Control Act - BImSchG) are often required, where stocking density is examined in detail.
4. For species without specific regulations (e.g., cobia, rohu), a husbandry concept based on scientific knowledge and in observance of general animal welfare must be submitted.

Summary: There is no EU-wide, aquaponics-specific stocking density table. The permissible density results from the interplay of national animal welfare law, fertilizer law, and the practical limits of your specific aquaponics system design. Consultation with the responsible veterinary and environmental authorities before planning is essential.

Context:

• Stocking density
• Stocking densities Ecoponics
• FCR Real Values
• Fish growth curve
• Limits for Ammonium in fishing waters
• El-Sayed Khater: Fish production in aquaponics systems
• FCR / Feed Conversion Rate