Which parameters are critical for african catfish farming in ras?
The critical parameters are temperature, dissolved oxygen, pH, ammonia, nitrite, nitrate, stocking density, feeding rate, hydraulics and redundancy of key equipment.
Technology - RAS for African catfish
Technology for growing African catfish in RAS systems
The warm clarium catfish is one of the most unpretentious objects of RAS: it breathes atmospheric air, tolerates high densities and turbid water. We analyze environmental parameters, design features, growth, feed and farm composition.
Juvenile African garie catfish (Clarias gariepinus)
Short answer
African catfish farming in RAS explains how to organize fish production with controlled water quality, oxygen, temperature, stocking density, feeding and routine operations. African catfish allows high stocking density but requires warm water, sanitation discipline and a clear sorting logic.
What is a RAS farm for African catfish?
The RAS farm for clary catfish is a farm with repeated use of water, where the environment is maintained by a cleaning and preparation system. The key factor of technology is warm mode 26–28 °C and high planting density. Unlike trout and sturgeon, adult catfish breathe atmospheric air through the epibranchial organ, so water oxygenation is often not necessary in the commercial block.
The main feature of the species
The epibranchial organ allows the catfish to breathe air: by 3–5 d almost all individuals switch to atmospheric respiration, and water oxygen ceases to be limited. Oxygenation occurs only in the larval block.
History and taxonomy
Clary catfish belongs to the “cat fish” group: fatty meat without intermuscular bones, fillet yield of more than 50% of live weight, preservation of taste when frozen. In Africa and a number of warm countries it is one of the main types of table fish.
- The Netherlands: First Research Material - 1977 g., first farms - 1980 g.
- In the 1990s, farms appeared in Belgium, Germany, Hungary, the Czech Republic and Russia.
- Brought to Russia from Holland to the Lipetsk Iron and Steel Works in 1996 g.
- The Netherlands grows about 1000 t clariid catfish per year.
Basic Environment Settings
Optimal cultivation regimes and water quality guidelines.
| Parameter | Optimum | Comment/critical |
|---|---|---|
| Temperature | 26–28 °C | Maximum growth and feed absorption. Discomfort <20 and >35 °C; <15 °C - sick and almost does not grow; lethal ~6–8 °C. |
| Oxygen (O₂) | Important in the larva | Catfish breathe through gills only at the larval stage; s ~500 mg the epibranchial organ develops. Oxygenation is only a larval block. |
| pH | 6,5–7 (in RAS ~7) | Acceptable 6.5–8.5; critical <6 and >9. |
| Suspension (TSS) | product 70–100; fry 30–50 mg/l | There was no direct relationship between suspended matter and growth/FCR; Catfish are tolerant of muddy water. |
| Hydrogen sulfide (H₂S) | not allow | Maximum concentration for commercial catfish ~2 mg/l. |
About ammonia
Catfish are significantly more tolerant of ammonia than sturgeon or trout; Toxicity increases with temperature and pH. For commercial fish at T=26 °C: pH 7 — ammonium nitrogen threshold at the outlet ~100 mg/l; pH 7,5 — 30–50 mg/l; pH 8 – no more than 10–15 mg/l.
Water parameters by stage
| Parameter, mg/l | Broodstock | Egg/larva | Fry up to 2 g | Fry up to 10 g | >10 g and product |
|---|---|---|---|---|---|
| Oxygen, O₂ | 4–5 | 4–5 | 3–4 | 2–3 | not critical* |
| NH₃-N | <1 | 0,05 | <0,34 | <0,34 | <0,5–1 |
| NO₂ | <0,2 | 0,2 | 0,2 | <0,5 | <5–8 |
| NO₃ | <50 | <50 | <50 | <100 | <1000 |
| CO₂ | <10 | <10 | <10 | — | — |
* Water O₂ requirements for commercial fish are not critical due to atmospheric breathing.
Growing options
Ponds
Dependence on season and temperature, limited controllability of conditions.
Forward flow
Growing on a tributary: simpler in design, but depends on the flow rate and water quality.
RAS
Year-round warm conditions, high density and controlled conditions with proper engineering.
Features of designing a RAS farm
The engineering specificity of catfish differs from trout and sturgeon - due to atmospheric respiration, thermophilicity and high densities.
- Pools: There are no restrictions on depth (catfish in the water column), but the volume of one pool is up to ~10 m³: in large areas, cannibalism and mortality increase and FCR worsens.
- Pool shape: on commercial catfish, the self-cleaning of round pools is reduced (the suspension does not settle) - any shapes are suitable (round, rectangular, square). This is not always applicable for larvae and fry.
- Water exchange: limiting factor - ammonium nitrogen; in practice 1 water change per hour.
- Oxygenation and aeration of water are not needed in the product block - the oxygenator is only in the larval block.
- Biofilter: high temperature and permissible ammonium increase oxidizing capacity; landmark - 1 g TAN for 1 m² protected loading area per day.
- Biofilter aeration more intense: no less 10 volumes per hour (for sturgeon/trout 6–8).
- Rough cleaning in front of the drum: thin-layer sedimentation tank or hydrocyclones.
- Drum filter works in difficult conditions (mucus, heat) - practical mesh 100 µm (on a larva/fry 60 are possible µm). For high-quality rough cleaning, you can do without a drum.
- Mechanical-biological filter on a static granule with a separate chamber after a floating load.
- Planting densities very high: project up to 350 kg/m³ (there were examples up to 500).
- Disinfection not necessary (catfish rarely get sick), but recommended for larvae/fry. UV: 15–20 W at 1 m³/hour (1.5–2 times higher than sturgeon/trout). Ozone: economical dose 10–15 mg/l.
- Pipelines overgrow more actively (suspension + heat) - revisions, cleaning and diameters with a margin.
Growth of catfish in RAS
Optimum 26–28 °C catfish grow very quickly: from eggs to 2.5–3 kg - in about 9 months.
Caviar → 2 gabout 1 month
2 → 20 gabout 3 weeks
20 → 300 gabout 2 months
300 g → 1.5 kgabout 3 months
1,5 → 2,6 kgabout 2 months
Total~9 months from caviar to 2.5–3 kg
Feed, density, survival
Daily feed intake
| Hitch | % by weight/day |
|---|---|
| up to 1 g | 6–10% |
| 1–100 g | 5–6% |
| 100–400 g | 3–4% |
| 400 g – 1 kg | 2–2,5% |
| 1,5–3 kg | 1,5–1,8% |
Planting Density
| Stage | Density |
|---|---|
| Larva up to 500 mg | 50–150 pcs/l |
| Baby up to 4 g | 20 pcs/l |
| 4–20(30) g | 5–10 pcs/l |
| 30–300 g | 1–1.5 pcs/l |
| 300 g – product | 0.8–1.5 pcs/l |
90–95%
Survival at commercial stages
~63%
Lives from eggs to final hatch
~1,09
Final Feed Ratio (FCR)
550–650
mg O₂/(kg h) at sample 1 g
Stages of the commercial cycle
Incubation
Tray incubators, Weiss incubators. Temperature 25–27 °C. Duration - on average 1 day.
Larva
Trays, ICA pools, rectangular pools, 25–27 °C. Keeping for ~2 days; Stage 1 2-3 weeks - before switching to air breathing (400-500 mg).
Juveniles and goods
Rectangular and round pools, 22–30 °C (optimum 26–28). Duration - according to the final sample.
Planting material
Fertilized eggs (often at the "eye" stage) or juveniles. When rearing from eggs, an incubation-larval block is included in the project, where 25–27 are critical °C and water quality.
Site and building
The key is to ensure a warm temperature of 26–28 °C and stable operation of water purification units.
- Communications: water, sewerage, 380 B, heating/heat generation.
- Zones: larval block (with oxygenation), commodity block, cleaning units, feed warehouse, sanitary areas.
- Technologically: inspection and cleaning of pipelines, stock of diameters; thermal insulation, ventilation and moisture removal.
Farm composition
- Incubation and larva (if grown from eggs)
- Fry area (up to 10 d) - increased requirements for water
- Product area (until the final hitch)
- Rough cleaning (hydrocyclones/thin-layer sedimentation tank)
- Biofilter (floating loading) + mech-bio filter on granules
- Drum filter (if provided)
- Pumping station, instrumentation and automation, automatic feeding
- Disinfection (optional; required for larva/fry)
Equipment
Composition of RAS equipment for African catfish. The list depends on the water and type of fish.
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Fish tanks≋
Rough cleaninghydrocyclones / thin layer⊙
Drum filter▤
Biofilterfloating loading▦
Mech-bio filtersinking load⊳
Pumps☀
DisinfectionoptionalpH
pH adjustment system⊞
Automatic feedingResource costs
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Electricity
Recirculation pumps, intensive biofilter aeration, automation. Oxygenation of water is only a larval block.
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Warmth
Maintenance 26–28 °C is the key flow rate, depending on the building and climate.
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Water
Make-up + drum wash water. At 1 water exchange/hour, the balance is calculated using ammonium.
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Stern
Main OPEX. Feeding rates and FCR are recorded in production tables.
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Planting material
Caviar or fry; To get started, it is often profitable to purchase from trusted suppliers.
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Staff
Fish farmer + RAS operator/engineer, sorting and maintenance personnel.
Dimensions of fish tanks
| Stage | Optimal values | Valid values |
|---|---|---|
| Larva up to 500 mg | Trays h water up to 0.5 m, volume 1–2 m³; pools h up to 0.8 m, D up to 2 m | Swimming pools h up to 1 m, D up to 3 m |
| Baby up to 5 g | Trays h up to 0.5 m, volume 1–2 m³; pools h up to 1.2 m, D up to 3 m | Pools h up to 1.5 m, D up to 4 m |
| Juveniles up to 300 g and product | Volume up to 10 m³, h water up to 1.5 m | Volume up to 15 m³, h water up to 2 m |
| RMS (uterine) | Volume 1–3 m³, h up to 1.5 m | Volume up to 10 m³, h up to 1.5 m |
Project implementation
Technology design — our profile (service “Design of fish farms”).
Building design.
Supply of equipment.
Construction of a building.
Installation of technology.
Launch and stocking.
Let's design a farm for African catfish
From environmental parameters and water exchange to the selection of equipment and working documentation.
Completed projects
RAS farms for African catfish that we sold: Kazakhstan (20 t/year), Samara region (40 t/year), Yaroslavl region (20 t/year).
FAQ
Frequently asked questions
Clear answers to the questions that usually appear before a RAS fish farm project starts.
Can standard equipment be used without calculation?
It is risky. Equipment must match the species, biomass, feed load, water quality and building layout. A generic set can lead to weak filtration, unstable oxygen or difficult maintenance.
How is the technology selected for a project?
The choice depends on fish species, target capacity, water source, climate, available building, energy costs, staff skills, market format and the required level of automation.
Calculate a farm for African catfish according to your conditions
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