I. Abstract

In 2026, an increasing number of shrimp farming enterprises are converting open-pond systems into recirculating aquaculture systems (RAS) to overcome yield bottlenecks and prevent bacterial and viral diseases. This guide explains in detail how a closed-loop recirculating aquaculture system design can increase shrimp survival rates from 40-50% to 78-85%, reduce antibiotic use by 80-90%, and enable year-round multi-cycle farming — no longer constrained by season or weather.

II. Where is the ‘ceiling’ for traditional prawn farming?

For decades, pond shrimp farming has had to contend simultaneously with three major threats: pathogens, fluctuations in water quality and unpredictable weather. Diseases alone account for the lion’s share of global aquaculture losses — approximately 80% of farmed shrimp mortality is linked to whitespotsyndromevirus (WSSV); vibriosis (red leg disease and acute hepatopancreatic necrosis) caused by pathogens such as Vibrio parahaemolyticus, as well as parasites such as Enterocytozoon hepatopenaei (EHP), also result in stunted growth and widespread mortality.

The fundamental problem with open-pond systems is that the farming environment is uncontrollable. Rainfall alters pH levels, overfeeding drives up ammonia-nitrogen and nitrite levels, and every water intake may reintroduce viruses. Survival rates in traditional systems have long remained at 40-50%, and farmers often rely on antibiotics just to make it to harvest.

III. How do recirculating aquaculture systems increase shrimp yields?

1. Higher survival rates and stocking densities

Recirculating aquaculture systems for shrimp replace the practice of large-scale drainage and refilling with a closed-loop water circulation system: physical filtration, protein skimming, biological filters, UV disinfection and intelligent aeration work round the clock to maintain dissolved oxygen, pH, total ammonia nitrogen and nitrite within stable ranges. Stable water conditions mean less stress and smoother moulting, with survival rates reaching 78-85%. This directly supports higher stocking densities and biomass per unit volume of water. Field data from winter greenhouses show that the recirculating aquaculture system yields approximately 9.5 kg/m³ of water, compared to approximately 7.35 kg/m³ in conventional greenhouses, representing a yield increase of over 30% for the same volume of water.

2. Multiple Crops Year-Round and Continuous Market Supply

With controllable indoor water temperature and lighting, there is no longer an ‘off-season’ for shrimp farming. Three to four crops can be raised annually (compared to just one or two in traditional systems), and production can be rolled out in batches through staggered stocking, ensuring a stable year-round supply to customers.

3. Precision Feeding and Data-Driven Management

Automatic feeders are linked to water quality sensors, significantly reducing waste from uneaten feed (which is not only the largest cost item but also a trigger for Vibrio outbreaks). Each rearing cycle can be quantitatively assessed, the feed conversion ratio (FCR) is continuously optimised, and the size of the shrimp at harvest is more predictable.

IV. How does RAS overcome bacterial and viral diseases?

1. Biosecurity: Keeping pathogens out

The strongest commercial case for recirculating aquaculture systems is biosecurity. Multi-stage filtration combined with UV and ozone disinfection achieves a pathogen removal rate of over 99.9%, thereby severing the transmission chain through which WSSV, yellow head virus and Vibrio bacteria invade ponds via the inflow water. In closed facilities, RAS shrimp survival rates have risen to 78%-85%, far exceeding the historical levels of 40%-50% seen in traditional ponds — a gap that is directly reflected in farming profits.

2. Antibiotic-free farming and premium pricing

With reduced disease pressure, the use of medication consequently decreases. Recirculating aquaculture systems typically reduce antibiotic usage by 80%-90%. ‘Antibiotic-free prawns’ command a price premium of 15%-20% in export markets — turning disease prevention and control into a revenue advantage.

3. Multi-tiered health management

Reliable RAS programmes also incorporate a three-tiered defence system: pre-stocking multi-pathogen testing of SPF (specific pathogen-free) juveniles for WSSV, EHP and Vibrio species; replacement of conventional medication with immunopolysaccharides, probiotics (lactic acid bacteria, Bacillus spp.) and yolk antibodies (IgY); and the use of portable qPCR and LAMP rapid testing kits to detect and address abnormalities on the same day.

V. Comparison of Technical Parameters: Traditional Ponds vs. Recirculating Aquaculture Systems for Shrimp

To provide a more intuitive comparison of the differences between recirculating aquaculture and traditional pond farming, a detailed comparison is presented across eight aspects: survival rate, stocking density, annual harvests, pathogen control, antibiotic usage, yield per unit volume of water, water intake and discharge, and dependence on climatic conditions.

Table 1: Comparison of Traditional Ponds and Recirculating Aquaculture Systems

VI. Frequently Asked Questions (FAQ)

Q1: Can recirculating aquaculture systems (RAS) for shrimp prevent and control White Spot Syndrome Virus (WSSV)?

A: No system can eliminate the risk entirely, but closed recirculating aquaculture systems cut off the primary route of transmission — contaminated inflow water. When combined with SPF fry, UV/ozone disinfection and strict biosecurity protocols, WSSV outbreaks will become rare and manageable.

Q2: What stocking densities can be achieved in recirculating aquaculture systems for prawns?

A: As dissolved oxygen and water quality can be precisely controlled, RAS can support stocking densities far higher than those in ponds. The practical upper limit depends on filtration capacity and feeding strategies — Wollize can assist with system selection and feasibility assessments based on your target yield.

Q3: How does RAS reduce the use of antibiotics in shrimp farming?

A: Stable water quality reduces stress and bacterial load, whilst probiotics and immune enhancers replace conventional medication. Most recirculating aquaculture systems can reduce antibiotic use by 80%–90% and enable the sale of antibiotic-free shrimp.

Q4: Is recirculating aquaculture for shrimp profitable?

A: RAS involves higher initial investment, but this is offset by more harvest cycles, higher survival rates, lower medication costs and a premium selling price. In field trials conducted in heated greenhouses during winter, a 800-cubic-metre recirculating system generated over US$12,000 more profit per season (3 months) than a conventional heated greenhouse.

Q5: What equipment is required for a recirculating aquaculture system for shrimp?

A: Core modules include drum/disc filters, protein skimmers, fluidised-bed biological filters, UV/ozone units, intelligent aeration systems, online water quality sensors and a central control cabinet — it is recommended that these be designed as an integrated system to avoid a patchwork of different brands.

VII. Contact Us

Plan your recirculating aquaculture system (RAS) project for shrimp farming with Wolize. Whether you are retrofitting an existing shrimp farm or constructing a new indoor aquaculture facility, Wolize provides one-stop RAS equipment and engineering services — from process design and equipment selection to installation, commissioning and after-sales training. Please feel free to contact our team for a free layout assessment and target yield calculation.

Figure 1: Recirculating aquaculture system for Shrimp (Penaeus orientalis)