How Technology Is Changing the Way UK Fish Farms Manage Water

Ask most people where their salmon or trout comes from, and they'll picture a Scottish loch or a chalk stream somewhere in the English countryside. The reality, increasingly, is rather different. A growing share of the UK's farmed fish is produced in land-based facilities where every litre of water is carefully controlled, filtered, and recirculated, and where the engineering behind that process matters enormously.

The Shift Towards Controlled Water Systems

Traditional flow-through fish farming, where fresh water runs in, through the tanks, and out, is giving way to something more sophisticated. Recirculating Aquaculture Systems, known in the industry as RAS, treat and reuse water rather than continuously drawing from rivers or the sea. The fish stay in the same water; the water itself is cleaned, oxygenated, and temperature-regulated in a continuous loop.

It's a setup that allows farms to operate year-round regardless of weather, manage disease risk more effectively, and reduce the environmental footprint of production. Land-based RAS facilities are also increasingly attractive to investors for exactly these reasons: you're not at the mercy of tidal conditions or seasonal water temperatures.

The catch, if you'll pardon the expression, is that running this kind of system demands serious infrastructure. Particularly when it comes to water movement.

Why Pumping Technology Is Central to Fish Health

Water in a RAS facility doesn't stand still. It circulates through mechanical filters, biofilters, UV disinfection units, aeration systems, and back to the tanks, often continuously, 24 hours a day. Any interruption to that flow can compromise oxygen levels within minutes. For fish densities typical of a commercial operation, that's a significant welfare and financial risk.

That's why the specification of aquaculture pumps matters far more than many first-time operators anticipate. The pumps used in RAS need to handle seawater, freshwater, and brackish water, often with particles present, without degrading quickly or requiring frequent maintenance stops. Downtime in a fish farm isn't like downtime in a factory; you can't just pause production.

DESMI, a Danish engineering company with a substantial aquaculture division, designs centrifugal pumps specifically for these environments. Their systems are built to operate continuously at over 80% efficiency under high-flow, low-pressure conditions, which is the typical demand profile in a recirculating setup.

Disinfection: the Role of UV in Modern Fish Farms

Alongside water movement, pathogen control is one of the most pressing technical challenges in intensive fish farming. Virus and bacteria outbreaks have historically caused significant stock losses across the industry, and chemical treatments bring their own complications in a closed-loop system.

UV disinfection has become the standard approach in modern RAS facilities. By exposing water to ultraviolet light at a carefully calculated dose, harmful microorganisms are neutralised without introducing chemicals into the water supply. The effectiveness depends on water clarity and the UV dose applied, both of which need to be matched to the specific pathogens of concern for a given species and location.

A Growing Sector With Room to Expand

The UK aquaculture industry is still relatively modest compared to Norway or Scotland's offshore salmon sector, but land-based production is growing. According to Seafish, the potential to expand UK aquaculture exists not just in established species like trout but in newer ventures such as warm-water shrimp farmed in on-land RAS systems. Regulatory and water quality challenges have historically slowed growth, but investment in better infrastructure is gradually shifting that picture.

What This Means for the South West

Devon and the wider South West have a seafood tradition that stretches back centuries, and interest in land-based aquaculture has been growing steadily in the region. As more operators look to build or upgrade RAS facilities, the decisions they make about water management infrastructure, such as pumps, UV systems, and monitoring technology, will shape how viable and sustainable those operations turn out to be. It's not the most visible part of the industry, but it's arguably the most critical.