Nursery Tank Design for Fingerling Production

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-14

Key Takeaways

• Tank geometry and water depth are critical for fingerling survival and growth uniformity. Circular or square-round tanks with self-cleaning bottoms and shallow water depths (0.6-1.0 meter) facilitate waste removal and access to surface feed, outperforming rectangular designs.
• Stocking density is system-dependent and directly impacts water quality management. Flow-through systems support 100-300 fingerlings/m³, while recirculating systems with robust biofiltration can achieve 500-1000 fingerlings/m³, necessitating careful biofilter sizing based on daily feed input.
• Oxygen is a primary limiting factor, requiring continuous aeration and backup systems. High metabolic rates of fingerlings necessitate proactive planning for dissolved oxygen levels above 5 mg/L, with fine bubble diffusers and potential supplemental oxygen for high-density recirculating systems.
• Efficient solids removal via self-cleaning tank bottoms and appropriate drainage is paramount to prevent ammonia spikes. Central drains with adequate slope (10% for circular, 5-10% for square-round) and appropriately sized drain lines are essential for rapid waste evacuation.
• Biosecurity protocols, including quarantine and water treatment, are vital for disease prevention. Separate observation tanks for new stock, disinfection of equipment between tanks, and potential UV sterilization or ozone treatment of incoming water mitigate pathogen introduction and spread.
• Recirculating systems require biofilter sizing based on daily feed input, not tank volume, to manage nitrification. A moving bed biofilter, for example, can process 300-500g of ammonia nitrogen per m³ of media per day, requiring careful calculation based on projected feed consumption.

Raising healthy fingerlings starts long before the first fish is stocked. The nursery tank is the controlled environment where larvae and fry transition into hardy, transport-ready fingerlings, and its design determines survival rates, growth uniformity, and disease pressure. This guide covers the complete planning process for a fingerling nursery system, from site selection and tank geometry to water recirculation, aeration, feeding strategies, and biosecurity. It is written for fish farmers, hatchery managers, and agricultural planners who are designing a new nursery facility or upgrading an existing one.

At a Glance

• Tank shape matters: Circular or square-round tanks with self-cleaning bottoms outperform rectangular tanks for fingerling survival and uniform growth.
• Water depth should stay shallow: Keep nursery water depth between 0.6 and 1.0 meter to allow fingerlings easy access to surface feed and to simplify waste removal.
• Density depends on the system: Flow-through tanks can hold 100 to 300 fingerlings per cubic meter, while recirculating systems with robust biofiltration can support 500 to 1000 per cubic meter.
• Water exchange rates of 100 to 300 percent per hour are common in nursery systems, with higher rates for warm-water species.
• Oxygen is the first limiting factor: Plan for continuous aeration and backup oxygen supply before you stock fish.
• Self-cleaning tank bottoms with central drains remove solid waste within minutes, preventing ammonia spikes.
• Sizing the biofilter for a recirculating nursery requires calculating daily feed input, not tank volume.
• Start with a quarantine protocol: New fingerlings need observation tanks separate from the main nursery system.

Planning the Nursery System

The design of a fingerling nursery tank begins with a clear set of production goals. You need to know the target species, the number of fingerlings you intend to produce per cycle, the length of the nursery phase, and whether you will operate a flow-through, static, or recirculating system. These decisions determine tank size, water supply requirements, and equipment needs.

Define Your Production Target

Start by calculating the number of fingerlings you need per production cycle. This number drives every other design decision. For example, if you plan to stock 50,000 grow-out ponds per year and you expect 70 percent survival through the nursery phase, you need to hatch or acquire roughly 72,000 larvae. If your nursery phase lasts 30 days and you want to operate three batches per year, your nursery system must hold about 24,000 fingerlings at any given time.

Work backward from your target to determine tank volume. If you plan a flow-through system with a stocking density of 200 fingerlings per cubic meter, a 24,000-fingerling nursery requires 120 cubic meters of tank volume. That volume could be split into four 30-cubic-meter tanks or six 20-cubic-meter tanks. Smaller tanks give you more management flexibility and make disease control easier, since you can isolate a sick cohort without disrupting the entire system.

Choose the System Type

Three basic water management approaches are available for nursery systems.

Flow-through systems use a continuous supply of clean water from a well, spring, or surface source. Water enters the tank, passes through, and exits to waste. These systems are simple to operate and require no biofiltration, but they demand a reliable water source with adequate flow. A nursery tank of 10 cubic meters at a 200 percent hourly exchange rate requires 20 cubic meters of water per hour, or about 5,300 gallons per hour. That is a substantial water requirement that many farms cannot sustain.

Static systems hold water without continuous exchange. They rely on aeration and periodic water changes to maintain water quality. Static nursery tanks are the simplest to build and the cheapest to operate, but they are also the riskiest. Ammonia and nitrite accumulate quickly at fingerling densities, and oxygen depletion can occur within hours if aeration fails. Static systems are best suited to low-density operation or short-term holding.

Recirculating systems treat and reuse water through mechanical and biological filtration. They use far less water than flow-through systems, typically 5 to 10 percent of system volume per day in replacement water. Recirculating systems offer the most control over temperature and water quality, but they require more capital investment, more electrical power, and more operator skill. A well-designed recirculating nursery can support fingerling densities of 500 to 1000 per cubic meter, which makes it the most space-efficient option.

Site Selection for the Nursery

The nursery facility should be located where water quality is consistent and where you can protect fish from temperature swings and contamination. If you use groundwater, test it for pH, hardness, alkalinity, iron, and hydrogen sulfide before construction. Groundwater with high iron content can stain gills and stress fingerlings. Surface water carries the risk of wild fish, parasites, and agricultural runoff.

Place the nursery building close to your water source to minimize pumping costs. The building should have a concrete floor sloped to a central drain so you can wash down tanks and aisles. Provide adequate lighting for inspection but avoid direct sunlight on tanks, which promotes algal blooms and temperature fluctuation. Insulation and climate control are worthwhile investments in regions with extreme seasonal temperatures.

Tank Geometry and Materials

The shape and construction of the nursery tank affect water flow, waste removal, and fish behavior. Fingerlings are delicate and easily stressed by poor water circulation or sharp corners where waste accumulates.

Circular Tanks

Circular tanks are the preferred design for fingerling nurseries in most commercial operations. Water enters tangentially near the tank wall, creating a circular flow pattern that carries solid waste toward a central drain. This self-cleaning action keeps the tank bottom clean and maintains uniform water quality throughout the tank.

The diameter-to-depth ratio for circular nursery tanks should be about 3 to 1 or 4 to 1. A 3-meter-diameter tank with a 0.75-meter water depth has a volume of about 5.3 cubic meters. The shallow depth allows fingerlings to reach the surface easily for feeding and allows light to penetrate for natural feeding behavior. Deeper tanks create stratification and make waste removal less efficient.

Water inlet design matters more than most farmers realize. A single tangential inlet creates a rotating flow that pushes waste toward the center drain. The inlet should be positioned below the water surface to reduce splashing and noise, but high enough to create good circulation. Some designs use multiple inlets at different depths to prevent dead zones.

Square-Round Tanks

Square-round tanks are square tanks with rounded corners and a sloped bottom that drains to a center outlet. They offer better space utilization than circular tanks when you are fitting multiple tanks into a rectangular building. The rounded corners prevent dead zones where waste accumulates and where fingerlings can become trapped.

Square-round tanks require careful inlet placement to achieve good circulation. A single inlet is rarely sufficient. Most designs use several inlet nozzles positioned to create a rotating flow pattern around the tank perimeter. The bottom should slope toward the center at a grade of at least 5 to 10 percent.

Rectangular Tanks

Rectangular tanks are common in older hatcheries and in situations where space is constrained. They are easier to build and can be made from concrete, fiberglass, or wood frames with liners. However, rectangular tanks have significant disadvantages for fingerling production.

Water flow in a rectangular tank moves in a linear path from inlet to outlet, leaving dead zones in the corners and along the sides. Solid waste settles in these areas and decomposes, releasing ammonia and consuming oxygen. Fingerlings tend to congregate near the inlet or outlet, creating uneven densities and variable growth. If you must use rectangular tanks, install multiple inlets along one end and a collection trough along the opposite end to improve flow distribution. Plan to clean the tank bottom manually several times per day.

Tank Materials

Fiberglass is the most common material for commercial nursery tanks. It is lightweight, smooth, non-toxic, and easy to clean. Fiberglass tanks are available in prefabricated shapes and sizes, and they can be repaired if damaged. The initial cost is higher than other options, but the longevity and ease of maintenance usually justify the investment.

Polyethylene and polypropylene tanks are durable and less expensive than fiberglass. They are available in round and square-round configurations. These tanks are resistant to corrosion and do not leach harmful compounds into the water. They can be difficult to repair if cracked, and they may deform under high temperatures or heavy loads.

Concrete tanks are permanent structures that are well suited to large-scale nursery operations. They are strong, stable, and can be built to any size. Concrete requires a smooth, sealed surface to prevent fish abrasions and to make cleaning easier. Epoxy coatings or food-grade paints are necessary to protect the concrete and create a smooth finish. Concrete tanks are more difficult to modify than fiberglass or plastic tanks.

Tank Color

Tank color influences fingerling behavior and feed efficiency. Light-colored tanks, such as white or light gray, make fish more visible for inspection and help you spot disease or abnormal behavior early. However, light-colored tanks can cause fingerlings to feel exposed and increase stress in some species.

Dark-colored tanks, such as dark green, blue, or black, provide a sense of security for fingerlings and can improve feeding response. Dark backgrounds make it easier for fry to see live prey such as rotifers and artemia. The tradeoff is that dark tanks make it harder to observe fish and to see waste accumulation on the bottom.

A practical compromise is to use light-colored tank walls with a dark bottom. This combination gives you good visibility of the fish while providing a secure background. Some commercial nurseries use dark tanks for the first two weeks of the larval stage, then switch to lighter tanks as fingerlings become more robust.

Water Supply and Quality Management

Water quality is the single most important factor in fingerling survival. The nursery system must deliver water that is free of toxins, pathogens, and temperature extremes, and it must remove metabolic waste products continuously.

Water Quality Parameters

Fingerlings have specific water quality requirements that are often more restrictive than those of adult fish. The acceptable ranges below apply to most warm-water species such as tilapia, catfish, and carp. Cold-water species such as trout and salmon require cooler temperatures and higher dissolved oxygen levels.

Temperature management is critical in the nursery. Fingerlings grow faster at the upper end of their species temperature range, but they also require more oxygen and produce more waste at higher temperatures. Sudden temperature changes of more than 2 to 3 degrees Celsius cause stress and can trigger disease outbreaks. Design your water supply system to minimize temperature fluctuation, either by drawing from a stable groundwater source or by installing heaters or chillers.

Water Flow and Exchange Rates

The required water exchange rate depends on stocking density, feeding rate, and water quality. As a starting point, plan for an exchange rate of 100 to 300 percent of tank volume per hour in a flow-through nursery system. This means a 10-cubic-meter tank needs 10 to 30 cubic meters of water flow per hour.

In recirculating systems, the flow rate through the tank serves a different purpose. The tank water recirculates through the filtration system many times per day, but only a small percentage is replaced with new water. The recirculation flow rate should turn over the tank volume at least once per hour to maintain good mixing and waste removal.

Aeration and Oxygen Supply

Fingerlings have high metabolic rates relative to their body size, and they consume oxygen rapidly. At high stocking densities, oxygen can become depleted within minutes if aeration fails. Every nursery tank needs a reliable aeration system with backup power.

Air blowers and air stones or diffusers are the standard aeration method. The air blower should be sized to deliver 1 to 2 liters of air per minute per kilogram of fish biomass, or roughly 5 to 10 liters per minute per cubic meter of tank volume at typical nursery densities. Fine bubble diffusers are more efficient than coarse bubble diffusers because they create more surface area for oxygen transfer.

In high-density recirculating systems, supplemental oxygen may be necessary. Oxygen cones or low-pressure oxygen injection can maintain dissolved oxygen levels above saturation. Pure oxygen systems require careful monitoring to prevent supersaturation, which causes gas bubble disease in fingerlings.

Always install a backup oxygen supply. A simple system with a compressed oxygen cylinder and a pressure regulator can save your crop during a power outage. Battery-powered air pumps are another option, but they have limited runtime and may not be sufficient for high-density tanks.

Solids Removal and Drainage

Solid waste from uneaten feed and fish feces is the primary source of ammonia in the nursery. Removing solids quickly reduces the load on the biofilter and maintains better water quality. The tank bottom design and drainage system determine how efficiently solids are removed.

Self-Cleaning Tank Bottoms

A properly designed nursery tank has a conical or sloped bottom that directs solids toward a central drain. The slope should be at least 10 percent for circular tanks and 5 to 10 percent for square-round tanks. Water flow creates a circular motion that carries solids to the center, where they exit through the drain.

The central drain should have a standpipe or a screened outlet that allows water to exit while retaining fish. The drain diameter must be large enough to handle the maximum water flow without creating excessive suction that traps fingerlings. A common design uses a dual-drain system with a small center drain for solids and a larger side drain for the main water flow.

Drainage Design

Each tank should have an independent drain line so you can isolate a tank for cleaning or treatment without affecting other tanks. The drain line should be at least 4 inches in diameter for tanks up to 20 cubic meters, and larger for bigger tanks. The line should slope continuously to the collection point to prevent solids from settling in the pipe.

Install a valve or a standpipe system on each tank drain so you can control the water level and stop flow completely when needed. A simple standpipe inside the tank allows you to set the water depth by cutting the pipe to the desired height. When you remove the standpipe, the tank drains completely.

Settling Basins and Mechanical Filtration

In flow-through systems, the drain water goes to a settling basin or a mechanical filter before discharge. A settling basin slows the water so solids can settle out. The basin should be sized to hold at least 10 percent of the total daily water flow with a retention time of 30 to 60 minutes.

In recirculating systems, the drain water passes through a mechanical filter before entering the biofilter. Drum filters, bead filters, and sand filters are common options. The mechanical filter removes suspended solids that would otherwise clog the biofilter and contribute to ammonia production. Choose a filter with a mesh size of 40 to 60 microns for nursery applications.

Recirculating System Design

Recirculating aquaculture systems require careful engineering to maintain water quality at high stocking densities. The biofilter is the heart of the system, and its size is determined by the daily feed input, not by tank volume.

Biofilter Sizing

The biofilter converts ammonia into nitrite and then into nitrate through the action of nitrifying bacteria. The amount of ammonia produced is directly related to the amount of protein in the feed. As a rule of thumb, fish excrete about 30 grams of total ammonia nitrogen for every kilogram of feed consumed.

To size the biofilter, calculate the maximum daily feed input for your nursery system. If you plan to feed 50 kilograms per day across all tanks, the biofilter must handle about 1.5 kilograms of total ammonia nitrogen per day. A moving bed biofilter with plastic media can process roughly 300 to 500 grams of ammonia nitrogen per cubic meter of media per day. Your biofilter would need 3 to 5 cubic meters of media.

Biofilter Types

Moving bed biofilters use small plastic carriers that are kept in constant motion by aeration or mechanical stirring. They are self-cleaning and do not clog easily, which makes them well suited to nursery systems with variable solids loads. The carriers provide a large surface area for bacterial growth, typically 500 to 800 square meters per cubic meter of media.

Trickling filters pass water over a bed of media while air circulates upward through the bed. They provide both biofiltration and aeration, and they are simple to operate. However, they can clog with solids and require periodic cleaning. Trickling filters are best used in combination with effective mechanical filtration.

Fluidized bed filters use sand or fine media that is expanded by upward water flow. They offer very high surface area and efficient nitrification, but they require careful flow control to keep the media fluidized. A pump failure can cause the media to settle and compact, which is difficult to reverse.

Nitrification Startup

New biofilters require a startup period of 4 to 8 weeks before they can handle full feed loads. During this period, the nitrifying bacteria colonize the media and establish a stable population. You can accelerate the process by seeding the biofilter with media or water from an established system.

Plan your nursery production schedule around the biofilter startup. Stock the tanks at low density for the first few weeks and increase feeding gradually as the biofilter matures. Monitor ammonia and nitrite daily during the startup period. If ammonia or nitrite levels rise above safe thresholds, reduce feeding and increase water exchange.

Feeding Systems and Feed Management

Fingerlings require frequent feeding with high-quality feed to achieve good growth and survival. The feeding system must deliver the right amount of feed at the right time without wasting feed or contaminating the water.

Feed Types and Sizes

The nursery phase begins with fry that need microscopic live feed or finely ground starter feed, and progresses to fingerlings that can consume pelleted feed. The feed particle size should match the fish mouth size. As a general guide, the feed particle diameter should be about 20 to 30 percent of the fish mouth width.

Live feed such as rotifers and artemia is essential for the first days of many marine species and some freshwater species. After the first week, most species can transition to formulated starter feeds. Starter feeds are available in particle sizes from 100 to 500 microns for early fry, then 500 to 800 microns, and finally 1 to 2 millimeter pellets for larger fingerlings.

Feeding Frequency

Fingerlings have small stomachs and high metabolic rates, so they need frequent small meals rather than one or two large feedings. Feed fry 8 to 12 times per day during the first two weeks. As the fish grow, you can reduce feeding frequency to 4 to 6 times per day.

Use automatic feeders to maintain a consistent feeding schedule. Belt feeders, vibratory feeders, and demand feeders are all used in nursery systems. Automatic feeders reduce labor and ensure that feed is available throughout the day. However, you should still inspect feeding behavior daily to adjust feed rates and detect health problems.

Feed Rate Calculation

The daily feed rate is expressed as a percentage of fish body weight. Fry may consume 15 to 25 percent of their body weight per day, while larger fingerlings consume 5 to 10 percent. Calculate the total fish biomass in each tank by multiplying the number of fish by the average weight. Then multiply the biomass by the feeding rate to determine the daily feed amount.

Adjust the feed rate based on observed feeding behavior. If fish consume all the feed within 5 to 10 minutes, increase the amount. If feed remains on the bottom or in the water column after 30 minutes, reduce the amount. Uneaten feed is the main cause of water quality deterioration in nurseries.

Biosecurity and Disease Prevention

Disease outbreaks are the leading cause of fingerling mortality in nursery systems. A well-designed nursery includes biosecurity features that prevent pathogens from entering the facility and stop disease from spreading between tanks.

Facility Biosecurity

Control access to the nursery building. Only authorized personnel should enter, and they should follow a strict protocol that includes hand washing, foot baths, and dedicated clothing or boots. Visitors should be limited and should not enter the nursery if they have been on another fish farm within the past 48 hours.

Disinfect equipment between tanks. Nets, buckets, and other tools can transfer pathogens from one tank to another. Have a separate set of tools for each tank or disinfect tools with an approved disinfectant such as iodine or chlorine solution.

Water Treatment

If you use surface water, treat it before it enters the nursery. Filtration removes particulate matter and some pathogens. Ultraviolet sterilization or ozone treatment inactivates viruses, bacteria, and parasites. Sand filtration and cartridge filtration are common mechanical treatment methods.

Groundwater from wells is generally free of pathogens, but it may contain dissolved gases such as carbon dioxide or hydrogen sulfide. Aerate or degas well water before it enters the nursery to bring it to equilibrium with atmospheric conditions.

Quarantine and Observation

New fingerlings should be quarantined before they enter the main nursery system. A quarantine area with separate tanks, tools, and water supply allows you to observe new fish for signs of disease without risking the entire production system. The quarantine period should last at least 7 to 14 days, depending on the source of the fish and the species.

During quarantine, monitor fish for abnormal behavior, appetite loss, skin lesions, or mortality. If disease is detected, treat the fish in quarantine rather than moving them into the main system. Do not introduce fish from multiple sources into the same quarantine tank.

Monitoring and Recordkeeping

Successful nursery management depends on daily observation and careful recordkeeping. You cannot manage what you do not measure, and you cannot identify problems early without a baseline of normal conditions.

Daily Monitoring

Check each tank at least twice daily, preferably early morning and late afternoon. Observe fish behavior, feeding response, and water clarity. Measure dissolved oxygen and temperature at least once per day, and more often during periods of high temperature or high feeding rates. Measure pH and ammonia weekly, or daily during the first weeks of a new system.

Watch for early warning signs of stress or disease. Fish that are gasping at the surface, swimming erratically, or refusing feed are showing signs of distress. Reduced feeding response is often the first indicator of a water quality problem or an emerging disease.

Recordkeeping System

Maintain a daily log for each tank that includes the date, water temperature, dissolved oxygen, pH, ammonia, nitrite, feed amount, feeding response, and any observations of abnormal behavior or mortality. Record the number of dead fish removed from each tank daily.

Use the records to calculate survival rates, growth rates, and feed conversion ratios. These metrics tell you whether the nursery system is performing as expected and help you identify problems before they become catastrophic. A sudden increase in daily mortality should trigger an immediate investigation.

Decision Thresholds

Establish clear thresholds for action based on water quality and fish behavior. If dissolved oxygen falls below 5 mg/L, increase aeration and reduce feeding. If ammonia or nitrite exceeds safe levels, reduce feeding and increase water exchange. If mortality exceeds 1 percent of the tank population per day for two consecutive days, contact a veterinarian or fish health specialist.

Common Mistakes in Nursery Tank Design

Many nursery failures trace back to design errors that could have been avoided with better planning. The following mistakes are the most common.

Oversizing Tanks

Large tanks are harder to manage than small tanks. Water quality varies more across a large tank, and it is more difficult to observe fish and to remove dead fish promptly. If one tank becomes contaminated, you risk losing a larger portion of your production. Use smaller tanks to gain management flexibility.

Undersizing the Biofilter

The biofilter is the most common bottleneck in recirculating nursery systems. Farmers often size the biofilter based on tank volume rather than feed input, which leads to chronic ammonia and nitrite problems. Size the biofilter for the maximum daily feed rate, then add a safety margin of 25 to 50 percent.

Inadequate Backup Power

Power outages are inevitable, and they are deadly in high-density nursery systems. Without aeration, dissolved oxygen can drop below lethal levels within 30 minutes. Install a backup generator that automatically starts when the main power fails, and test it monthly.

Poor Drainage Design

Tanks that do not drain completely are difficult to clean and can harbor pathogens between production cycles. Design the tank bottom with adequate slope and install drains that allow complete emptying. The drain line should be large enough to handle maximum flow without backup.

Ignoring Water Temperature Control

Fingerlings are sensitive to temperature fluctuation. A nursery that relies on ambient air temperature without heating or cooling will experience growth slowdowns and disease outbreaks during seasonal transitions. Install heaters or chillers sized to maintain the target temperature even during extreme weather.

When to Call a Veterinarian or Extension Agent

You should contact a fish health professional in the following situations.

• Daily mortality exceeds 1 percent of the tank population for two or more consecutive days.
• Fish show signs of a contagious disease such as skin lesions, fin rot, or abnormal swimming behavior.
• You observe gill damage, pale gills, or fish gasping at the surface despite adequate dissolved oxygen.
• Water quality parameters remain outside safe ranges despite corrective actions.
• You suspect a toxin or chemical contamination in the water supply.
• You plan to introduce fish from a new source and need guidance on quarantine protocols.
• You are designing a new nursery system and want a professional review of your water treatment and filtration plans.

A veterinarian with fish health experience can perform a necropsy to identify the cause of mortality and recommend treatment. An extension agent can help you evaluate your system design, water quality management, and production practices. Both are valuable resources that can save you money and prevent losses.

Frequently Asked Questions

What is the best tank shape for fingerling production?

Circular tanks are the best choice for most nursery operations. The circular water flow creates a self-cleaning action that carries solid waste toward the central drain, maintains uniform water quality, and reduces stress on fingerlings. Square-round tanks are a good alternative when you need to maximize space utilization in a rectangular building. Avoid rectangular tanks for nursery production because they create dead zones and uneven water quality.

How deep should a fingerling nursery tank be?

Keep the water depth between 0.6 and 1.0 meter for most species. Shallow water allows fingerlings to reach the surface easily for feeding, improves light penetration, and makes it easier to remove waste. Deeper tanks create stratification and make it harder for fingerlings to access surface feed. The diameter-to-depth ratio should be about 3 to 1 for circular tanks.

What stocking density can I use in a nursery tank?

The stocking density depends on your system type. A flow-through system with 100 to 300 percent hourly water exchange can support 100 to 300 fingerlings per cubic meter. A recirculating system with a properly sized biofilter can support 500 to 1000 fingerlings per cubic meter. Start at the lower end of the range and increase density only as you gain experience and confidence in your water quality management.

How much water flow does a nursery tank need?

In a flow-through system, plan for an exchange rate of 100 to 300 percent of tank volume per hour. A 10-cubic-meter tank needs 10 to 30 cubic meters of water flow per hour. In a recirculating system, the recirculation flow rate should turn over the tank volume at least once per hour, but only 5 to 10 percent of the system volume is replaced with new water daily.

How do I size the biofilter for a recirculating nursery?

Size the biofilter based on the maximum daily feed input, not tank volume. Fish excrete about 30 grams of total ammonia nitrogen per kilogram of feed. A moving bed biofilter can process roughly 300 to 500 grams of ammonia nitrogen per cubic meter of media per day. Calculate your maximum daily feed rate, convert it to ammonia production, then divide by the biofilter processing rate to find the media volume needed.

What is the ideal water temperature for fingerling production?

The ideal temperature depends on the species. Warm-water species such as tilapia and catfish grow best at 27 to 30 degrees Celsius. Cool-water species such as trout and salmon prefer 10 to 15 degrees Celsius. Maintain the temperature within 2 to 3 degrees of the target and avoid sudden fluctuations, which cause stress and disease.

How often should I feed fingerlings?

Feed fry 8 to 12 times per day during the first two weeks, then reduce to 4 to 6 times per day as they grow. Use automatic feeders to maintain a consistent schedule. The daily feed amount should be 15 to 25 percent of body weight for fry, decreasing to 5 to 10 percent for larger fingerlings.

How long should I quarantine new fingerlings?

Quarantine new fingerlings for at least 7 to 14 days before introducing them to the main nursery system. Keep them in a separate tank with dedicated tools and water supply. Monitor them daily for signs of disease, abnormal behavior, or mortality. Treat any health problems during quarantine rather than moving the fish into the production system.

Related Farming Guides

This section will be populated with links to related farming guides on fish hatchery design, water quality management, recirculating aquaculture systems, and fingerling health management.

Related Clinical & Scientific Guides

• Pond Sediment Management and Dredging Options
• Indoor Aquaculture Facilities: Lighting and Insulation
• Greenhouse Aquaculture: Extending Growing Seasons

References

• FAO Fisheries and Aquaculture: https://www.fao.org/fishery/en
• USDA Aquaculture: https://www.usda.gov/topics/farming/aquaculture
• WOAH Aquatic Animal Health Code: https://www.woah.org/en/what-we-do/standards/codes-and-manuals/aquatic-code-online-access/
• FAO Animal Production and Health: https://www.fao.org/animal-production/en/
• WOAH (World Organisation for Animal Health): https://www.woah.org/en/home/

This article is educational and is not a substitute for veterinary diagnosis, treatment, public-health guidance, or regulatory reporting.