A canal farm is a layout where fish tanks are made in the form of long channels (trays) inside a single monolithic block, and water does not circulate through “kilometers of pipes,” but mainly by overflows between chambers. According to the cleaning principle, this is the same RAS - mechanical cleaning, biotreatment, degassing and oxygenation - but with different hydraulics and “Danish” type units.
ImportantA canal farm is not always a straight-through farm. Channel RAS can operate in a closed cycle (with make-up) and be very energy efficient.
Short answer
Raceway fish farming technology explains how to organize fish production with controlled water quality, oxygen, temperature, stocking density, feeding and routine operations. Raceway systems use long channels, managed water flow and service-friendly batch handling for different production stages.
What is this
What is a canal RAS farm
If a classic RAS is a set of free-standing pools (often round) connected by pipelines to water treatment, then a channel RAS is a single reinforced concrete block, where the sections are connected by overflows.
The sediment in the channel settles to the bottom and slowly moves towards the end of the channel, where fecal traps are provided.
History. Growing fish in long rectangular channels (raceways) has been used for more than a hundred years. Channel RAS came to the Russian Federation and the CIS largely through the experience of Denmark (trout). The technology is valued for its energy efficiency, simple hydraulics and failure resistance.
A cone with a ball “plug”: closed during operation, when dumping the ball is raised - the sediment leaves under hydrostatic pressure. Remove the heavy fraction and unload the filters.
Drum filter (optional)
Channel (open) design, stainless steel, sieve 40–60 microns. Relieves the sinking filter and increases the stability of biotreatment at high densities.
Biofilter MBBR
A floating load with nitrifying bacteria (ammonium → nitrates) is mixed by bubbling. It is advisable to rely on full oxidative power.
Sinking filter
Cascade of chambers with sinking loading (expanded clay/plastic): simultaneous mechanical and biological treatment. Flushing by blowing one at a time - without stopping the system.
Aeration field (degassing)
The bubbling zone, where CO₂ is “blown off” into the atmosphere. Diffusers at a given depth, connected to a blower. Stabilizes the gas regime.
Airlift
“Air lift”: air lifts water 30–40 cm (max ~50–70). For simple systems in air; saturation up to ~100%.
Propeller pumps
Pipe with a propeller: high water flow for low pressure (1–5 m). They are energy efficient and work in tandem with a duct oxygenator.
Channel oxygenator
Platform with nozzles in a U-shaped shaft: the jets entrain oxygen, saturation 13–18 mg/l (130–200%). For intensive modes and high densities.
Nodes at our sites
Fecal trapsDrum filter (channel)Aeration fieldAirliftChannel oxygenatorOxygen station
Pros and cons
Strengths and weaknesses
Pros
Easy to use
Energy efficiency
Failure proof
Cons
Large volume of concrete work
Not suitable for placement in existing buildings
Calculation
Principles of calculation and design
Practical guidelines from internal materials are specified by calculation based on the type of fish and the mode.
Parameter
Landmark
Planting Density
Trout: up to 100–120 kg/m³; on airlifts - up to 70 kg/m³.
Water exchange in channels
≈3 revolutions/hour in fry and commercial fish; 4–5 - in the larval stage.
Channel size
From 1x1 m, length 5–6 m (fry) to 5x2x30 m (commodity block).
Maintenance-friendly layout: access to traps, filters, flushing and discharge areas.
Consider in advance the collection and disposal of wash water and sludge (settlements/local treatment).
Equipment composition
Channels/trays (reinforced concrete), fecal traps and sludge disposal units
Channel-type drum filter (optional)
Biofilter MBBR (floating load)
Sinking filter (several chambers) + purging and flushing
Aeration field (degassing)
Airlift or propeller pumps - according to mode
Duct oxygenator (when running on pure O₂)
Compressors/blowers, oxygen, instrumentation and alarm systems, feeding
Implementation
How to build a canal farm
1
Technology design
2
Linking structures and layout (channels, recharge, discharge, site)
3
Concrete pouring and construction work (reinforced concrete block, channels, technical areas)
4
Equipment supply
5
Installation of components and communications (air, oxygen, automation)
6
Commissioning and spills: flushing, sediment discharge, mode adjustment
7
Launch and stocking
Construction of the block
Linking structures and siteChannel reinforcementConcrete block work
Experience
Canal Farm Projects
Republic of Karelia
Canal RAS farm for trout cultivation, capacity - 500 tons of marketable fish per year.
Kabardino-Balkaria
Canal RAS farm for growing Caspian salmon and trout.
Channel fish hatchery
FAQ
Frequently asked questions
Clear answers to the questions that usually appear before a RAS fish farm project starts.
Which parameters are critical for raceway fish farming technology?
The critical parameters are temperature, dissolved oxygen, pH, ammonia, nitrite, nitrate, stocking density, feeding rate, hydraulics and redundancy of key equipment.
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.
Application
Calculate a RAS channel farm for your conditions
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RAS channel farm - fish channels and piping
Channel fish hatchery