When people think about aquaculture, they often picture fish, water, and sea cages or tanks. Feed is usually seen as simple part of the picture — just pellets that make fish grow. But in reality, feed is the invisible engine that drives the entire aquaculture system.

You can think of feed as the fuel in a car. The fuel doesn’t just make the car move — it determines how hot the engine runs, how large the cooling system must be, and how efficiently the whole vehicle operates.

In aquaculture, feed affects how fast fish grow, fish health and welfare, how much waste is produced, and how the entire system must be designed and operated — especially in recirculating aquaculture systems (RAS). Understanding feed means understanding aquaculture at it's core.


Feed and Fish Growth

At its most basic level, feed provides fish with energy and nutrients. The quality of feed determines how efficiently fish convert feed into growth.

A good feed:

  • Supports steady growth
  • Improves fish health and welfare
  • Reduces waste

Feed is also usually the largest single operating cost in aquaculture. Just like improving fuel efficiency in a vehicle, small improvements in feed efficiency can lead to major savings.

At Saga Aqua, this is where system thinking begins: fish growth, feeding strategy, and system capacity are always considered together — never in isolation.


What Happens After Fish Eat?

Fish do not turn all feed into body mass. Just like humans:

  • Some nutrients go to growth
  • Some are used for energy
  • And some leaves the body as waste

One of the most important waste products is ammonia.

As fish digest protein in the feed, ammonia is released mainly through the gills. In water, this ammonia is measured as Total Ammonia Nitrogen (TAN).

Even small amounts of ammonia are harmful to fish, which is why waste handling is such a central part of system design.


Feed, TAN, and the Biofilter

In RAS, water is reused rather than constantly replaced. That means waste doesn’t disappear — it must be treated inside the system.

The biofilter works much like a wastewater treatment plant for a city. Beneficial bacteria convert toxic ammonia (TAN) into less harmful compounds. But just like a city treatment plant, the biofilter can only handle a certain load.

The relationship is simple:

  • More feed → more protein digested → more TAN
  • More TAN → higher demand on the biofilter

This is why feed rate directly determines how large and efficient the biofilter must be. Feed is not just a farm consideration — it is a core design parameter.

At Saga Aqua, biofilters are sized and integrated into the system based on realistic feeding scenarios, ensuring stable water quality even when production ramps up.


Why This Matters for System Design

When a RAS is designed properly, we don't don’t start with tanks — at Saga we start with feed.

Key questions include:

  • How much feed will be used per day on average?
  • How much feed will be used at max feeding?
  • How much TAN will that generate?
  • How large must the biofilter be?
  • How much water needs to be pumped to keep everything stable and the fish healthy and happy?

Higher feeding rates increase the need for:

  • Efficient water movement
  • Reliable ammonia removal
  • Stable water quality around the clock

If these relationships are underestimated, systems become sensitive, energetically inefficient, and difficult to operate.

Saga Aqua’s approach focuses on robust and energy-efficient design, where water flows, pumping, and filtration are matched precisely to the expected feed load.


Feed as a Planning Tool

In modern aquaculture, feed is used as a planning tool:

  • To size biofilters
  • To design water flow and pumping capacity
  • To predict waste production
  • To improve sustainability

Better feeding practices reduce nitrogen waste, and well-designed systems make that waste easier and cheaper to manage.

This combination — good feeding practice and smart system design — is key to long-term, reliable production.


In Summary

Feed is far more than just food:

  • It controls growth
  • It promotes fish health
  • It drives waste production
  • It determines biofilter size
  • It shapes the entire RAS design

By starting with feed, aquaculture systems can be designed to be stable, efficient, and resilient.

At Saga Aqua, everything starts with understanding feed and feeding — because we want to provide a well-designed system that gives good performance every day and for many years to come.