FritzZyme TurboStart 900 Validated in High-Density Shrimp Nursery Research
Texas A&M University–Corpus Christi and Texas AgriLife Research confirm rapid nitrification establishment in zero-exchange indoor systems
Researchers at the Texas AgriLife Research Mariculture Laboratory at Port Aransas and Texas A&M University–Corpus Christi conducted a production trial evaluating nitrogen control strategies for high-density, zero to limited water exchange shrimp nursery systems. FritzZyme® TurboStart® 900, Fritz’s consortium of marine nitrifying bacteria, was selected as the commercial inoculant for evaluation.
The Challenge
In high-density aquaculture systems, naturally occurring nitrifying bacteria do not establish population levels quickly enough to control toxic ammonia (TAN) and nitrite (NO₂-N) in the critical early stages of production. This is especially problematic in shallow-water indoor nursery systems with little or no water exchange, where there’s no dilution buffer for nitrogen compound buildup.
The research team sought to test whether a commercial nitrifying bacteria inoculant could accelerate bacterial colonization fast enough to protect juvenile shrimp during this vulnerable window.
The Trial
Four 1.5-meter square tanks were filled with seawater to a depth of 20 cm and stocked with PL12 Litopenaeus vannamei (Pacific white shrimp) at two densities:
- 19,445 juveniles/m³ (3,889/m²) — two tanks
- 38,890 juveniles/m³ (7,778/m²) — two tanks
Water quality parameters — including TAN, pH, alkalinity, NO₂-N, NO₃-N, and settleable solids — were monitored daily throughout the trial.
TurboStart 900 was applied during the establishment phase, averaging 551.25 ml per tank over the first 8 days. Nitrogen compound levels were tracked against a non-inoculated reference.
Results
The inoculated systems showed a marked reduction in both the intensity and duration of TAN and NO₂-N spikes compared to non-inoculated controls. A stable nitrifying bacteria colony was established within the treatment window.
Average juveniles harvested per tank: 26,778
Average TurboStart 900 used per juvenile harvested: 0.0206 ml
The trial achieved production densities exceeding 34,000 juveniles/m³ with good survival rates — demonstrating that high-output nursery production in low water volumes is achievable when nitrogen is actively managed from the start.
The researchers also evaluated NO₃-N control through dilution, finding it an effective short-term measure. Notably, removal of water and biofloc during exchange caused a temporary increase in NO₂-N, underlining the tradeoffs inherent in water exchange strategies.
Key Takeaways
- Nitrifying bacteria inoculation significantly reduced both the peak and duration of TAN and NO₂-N in high-density systems
- FritzZyme TurboStart 900 enabled rapid bacterial colony establishment within the first 8 days
- High-density production (>34,000/m³) with strong survival is achievable in minimal water volume when nitrification is properly seeded
- Water exchange for NO₃-N dilution carries tradeoffs and is not a complete long-term strategy
Texas AgriLife Research Mariculture Laboratory at Port Aransas and Texas A&M University–Corpus Christi, Texas A&M University System. Researchers: J. Crockett, A.L. Lawrence, J. Moeckel, B.A. Lingenfelter, S. Patnaik.
