Important Shrimp Culturing Practices

1. Soil Treatment:

1. Perform a mechanical/biological clean up of adduction channels bottom.

2. Sieve and discard floating organic matter before pumping water to reservoirs.

3. Perform a biological clean up of reservoir soil and water.

4. Use biologically pre treated reservoir water to fill the ponds and for compensating evaporation/filtration. Periodical reservoir water treatment with BZT® will maintain its soil health.

5. Cleaning the pond soil before Post Larvae (PL) stocking will provide a safer environment less prone to diseases and toxic compounds, and with most advantages for an easy and successful culture.

6. After harvesting and before pond filling apply CaCO3 only if pH is < 6.5 to increase it to 7.0.

7. Do not need to use CaCO3 as a soil sanitizer, since BZT® will digest solid residual organic substrates and other nutrients, making them non available to potentially pathogenic microorganisms.

8. Addition of CaCO3 or any substance that will raise pH > 9.0 will slow or stop BZT® digestion.

9. Depending on initial Total Organic Matter (TOM) in soil, first time soil treatment using of BZT® products in filled ponds should last from 1 to 4 weeks before PL stocking, or for a time until TOM is < 3 % and toxic nitrogenous compounds are under safe levels.

10. If you find excessive amounts of organic residuals, it would be preferable to dig and take out of the pond as much residuals as possible, as it will reduce overall organic loads and BZT® soil remediation time 

11. You do not need to fertilize before starting the BZT® soil treatment as we want to use residual solid organic wastes as nutrients for BZT® bacteria. Few days before PL stocking could fertilize if needed for getting proper turbidity levels.

12. In flooded pond during BZT® soil treatment, soil organic residues will be broken down and digested, and at the end being converted to CO2, water and BZT® bacterial mass.

13. Most of organic residuals are originally located in soil, and during its digestion they will be transferred to water and finally to atmosphere. Complete digestion and elimination of organic matter residuals from soil will take a certain time that will dependent on initial total organic matter (TOM), pH, CNP ratios, dissolved oxygen (DO), temperature, etc. 

14. At a certain time of BZT® treatment, if there is a sudden need to stock PL, if soil is already free of organic residuals, but water still contains nutrients under digestion, water can be discharged, and addition of new water could be used for stocking purposes, but BZT® Aquaculture is added 1 to 3 days before PL stocking.

15. In some fresh water cultures, necessity of PL stocking one day after pond filling along with BZT® Seeding application may demand high oxygen supply. If soil TOM is > 3.0%, it would be desirable to first treat the soil with BZT®, and when TOM is < 3.0 % discharge the water. Then fill again for PL stocking and start using only BZT® Maintenance applications.

16. For second cultures after using BZT®, shorter soil recovery periods would be needed due to a better soil quality at time of harvesting.

17. Liner: In ponds starting with clean liner, you may apply lower BZT® Seeding doses designed to control water, as is explained in the BZT® Application Chart.

2. Oxygen:

1. Around the clock maintain Dissolved Oxygen (DO) levels over 4.0 ppm, anywhere in the pond, and especially at the soil/water interface.

2. Check on paddle wheels capacity and proper alignment to get best distribution of organic wastes suspended evenly on the whole pond area.

3. Provide proper maintenance to electrical system to avoid failures. Have back-up equipment for substituting possible failures.

4. Increase aeration capacity in accordance to growth (3 HP/ton-shrimp).

5. Measure bottom and surface dissolved oxygen levels 4 times /24 hr, for corrections before damage.

3. Mechanical aeration:

1. Advisable in biomasses over 2 ton/ha.

2. In intensive cultures, 3 HP per ton of biomass should be enough.

3. When adjusting water C: N: P nutrient ratios, should have ready proper mechanical aeration on place. Proper ratio of C: N: P will result in a faster organic residual digestion and Oxygen demand.

4. When organic matter is reduced, DO demand will decrease.

5. Mechanical aeration should be running 24 hr/day to keep wastes in suspension and DO levels. May be lower at daylight hours.

6. Paddle wheel placement should provide even waste distribution in pond area and water column, avoiding spots where accumulation will create < 3.0 ppm DO levels at any time. 

4. Feeding:

1. Feeding with trays for better feeding and faster monitoring.

2. Feeding reduction in terms of kg/day or % protein should be made in case of excessive phytoplankton levels; appearance of toxic nitrogenous compounds and DO below 3.0 mg/L.

3. Reduce % protein in feeds in accordance to toxic nitrogenous compounds appearance, shrimp age and days of culture. This will result in the best utilization of proteins by shrimp, less toxic nitrogenous compounds in water/soil, and better shrimp growth.

4. Should apply feeds with high vitamin and mineral content.

5. BZT® bacteria will assist digesting excess of feeding and pond by products, improving water/soil quality and decreasing substrates for harmful microorganisms.

5. pH:

1. During soil recovery before pond filling, check soil pH, and may not apply CaCO3 if pond soil has a pH > 6.5.

2. In acidic soils, add enough CaCO3 just to raise pH to 7.0. It is easier and safer to raise pH with CaCO3 when needed, than to decrease pH with water exchange or acids.

3. BZT® bacteria need pH of 6.8 – 8.5 for optimal digestion. Maximum pH range is 6.0 to 9.0.

4. Stable water pH between 9.0 and 9.5 will reduce progressively BZT® bacteria digestion and performance in a lapse of few days, and pH over 9.5 will stop both enzyme and bacterial action. Stable pH over 10 will lead to an effective inactivation of bacteria. In the other side, pH below 6.0 will result in the same damage.

5. Measure pH at 5am and at 3pm to understand variation and proceed with corrections when necessary.

6. Secchi Disk (SD):

1. If SD readings for phytoplankton are below 30 cm, immediately increase mechanical aeration and decrease feeding quantity and/or % protein. Water exchange should be the last choice.

2. If SD levels are over 45 cm, nutrients should be measured for specific applications of N, P and Silicates.

3. Any time in the culture, and especially at the beginning, if phytoplankton levels are difficult to get, review NP ratios and concentrations, and you may reduce and split BZT® doses for applying at lower intervals until acquiring proper turbidity.

7. Fertilization:

1. Unbalanced nutrient ratios will result in water quality problems.

2. In waters with low nutrient load or in lined ponds, higher fertilization rates might be apply until feeding and other pond residuals are enough for supporting phytoplankton growth.

3. Nitrogenous compounds and Phosphate (PO4) analysis will provide data for correcting N: P ratios and concentrations.

4. Never apply organic fertilizers, as they can harbor or promote pathogenic bacteria growth.

5. Apply fertilizer preferably on sunny days for better nutrient utilization.

6. Application of Silicates is highly desirable for phytoplankton. BZT® bacteria will not compete for this nutrient, allowing reproduction of good quality plankton (diatoms).

8. Nitrogenous compounds:

1. When you find toxic nitrogenous compounds increasing including nitrates, an urgent correction action is required.

2. Appearance is increased in the presence of low DO, wrong pH or CNP ratios, PO4 not available in pond, or absence or improper BZT® application.

3. Ammonia: (NH3): High levels will destroy gill tissues. Should be < 0.02 ppm in fresh water, and < 0.13 ppm in salt water.

4. Nitrite (NO2-N): NO2 reacts with hemoglobin (Hb) to form methemoglobin, reducing respiration rates. Levels should be < 0.03 ppm in fresh water, and < 0.84 ppm in salt water. Levels should be < 2.0 ppm

5. Nitrate (NO3-N): NO3-N excess will result in high phytoplankton bloom and further detrimental effects on DO and water/soil quality.

6. BZT® bacteria will outcompete harmful bacteria and other microorganisms in using nitrogenous compounds. Blue-green algae which can fix atmospheric N, so it has to be controlled through other methods than nitrogenous compounds reduction.

9. Phosphorus:  in Lined ponds (HDPE)

1. Stable levels of PO4 at 0.3 ppm to 0.9 ppm in water would be enough to sustain proper phytoplankton and BZT® bacterial growth.

2. Starting cultures in lined ponds may have a P deficiency in water, as P would not be available from soil. It should be applied until finding stable levels shown above, or until SD levels are between 35 cm – 45 cm. Thereafter, feeding may provide enough P for all pond biochemical processes.

3. BZT® bacteria will outcompete harmful bacteria and other microorganisms in using PO4. Excessive PO4 presence may result in excessive cyanobacteria growth (if present) and toxicity to water.

10. Carbon: Nutrient: Phosphorus ratios in the system:

1. It is a critical parameter for BZT® bacterial digestion and pond stability.

2. Excessive organic wastes are detrimental to shrimp culture. It provides excess of nutrients for phytoplankton and beds for pathogenic microorganisms and diseases.

3. Phytoplankton and bacterial microorganisms may have similar requirements for N and P. When phytoplankton levels are fine, C, N and P levels shall be fine for BZT® bacteria.

4. For BZT® digestion, best C:N:P ratio in water/wastes is 100:5:1.

5. When phytoplankton concentration is too high, excess of feeding in terms of kg and % protein, and fertilization could be the cause.

6. If you find excessive N in water, instead of adding molasses (C) and P to correct C: N: P ratios, it is advisable to decrease protein % in feeds and feeding rate.

7. Excess of organic Nitrogen input in feeds will increase organic load in pond, toxic nitrogenous compounds, oxygen demand, which overall results in higher risks of shrimp mortalities.

8. Addition of molasses without enough DO (> 3 ppm) may produce fermented compounds which will increase the problems. Addition of molasses should be the last resource to use for adjusting CNP ratios.

11. Control of cyanobacteria (and production of toxins):

1. Cyanobacteria can grow in systems without organic Carbon, since they can drive the synthesis of carbohydrates from CO2 and H2O during photosynthesis, and can get N and P from organic wastes and soil, including N from atmosphere (N2).

2. In cultures with proper water and soil management, blue-green algae (cyanobacteria) can thrive and multiply if PO4 levels are > 0.3 ppm, which becomes the only real limiting factor, or if water exchange is used bringing fresh strains and nutrients.

3. By using BZT® bacteria, daily organic wastes will be kept at minimum, and will help to control excess of cyanobacteria growth.

4. To further control cyanobacteria growth, reduce/stop water exchange, and maintain PO4 levels at minimum (< 0.3 ppm).

12. Hydrogen sulfide:

1. The toxic effect is hypoxia.   

2. BZT® bacteria will outcompete sulfur bacteria in the utilization of organic wastes, which are indispensable to sulfur bacteria for producing H2S.

3. BZT® bacteria may utilize H2S as an energy source, converting it to elemental sulfur (S) and water (H2O).

4. Increasing DO levels will assist in reducing H2S production.

13. Alkalinity and Hardness:

1. Alkalinity will stabilize pH, and concentrations of Calcium Carbonate (CaCO3) between 80 ppm and 120 ppm will provide an adequate buffering capacity.

2. BZT® bacteria have similar alkalinity requirements as shrimp for best performance.

3. Adjustment of alkalinity should not raise pH > 8.5.

4. Hardness should be > 100 ppm.

14. Water Exchange:

1. Should use it only as last emergency resource.

2. By using BZT® products, water exchange can be minimized or stopped, since BZT® will take care of residuals.

3. If water is not pre treated, water exchange violates the principle of biosecurity. It can bring pathogenic microorganisms, excess of nutrients, toxic compounds and problematic cyanobacteria.

4. If for any reason of mismanagement or equipment failure the pond gets into dangerous dissolved oxygen levels, or water quality issues, first increase mechanical aeration, and as the last choice perform (bottom) water exchange.

5. Water exchange should be performed only with disinfected water and pre treated with BZT®.

6. Water exchange should not produce a significant change in Temperature (> 2 C) or salinity (> 2 ppt). Best Temperature is 32 C – 34 C

15. BZT® Product application:

1. It assists successful Aquaculture.

2. Start applying BZT® products as suggested by UTI tech department.

3. Later may adjust doses in accordance to pond dynamics.

4. Supervise BZT® application doses and protocols to determine whenever you need to adjust doses and procedures.

5. May activate the product for up to 4 hours using tap water, or may apply straight away mixing with pond water.

16. Data Transfer:

1. Data transfer to UTI tech department in a timely fashion will assure assistance for corrections on time.

2. Once UTI guides the client on how to design treatments and adjust applications, further BZT® management can be completely performed by end user.