Environmental guidance for your business in Northern Ireland & Scotland

Freshwater cages for fish farming

Fish farming in freshwater

Waste from fish cages can have a negative impact on the environment. It can:

  • smother bottom-dwelling animals and plants
  • remove oxygen from the water
  • increase the concentration of nutrients such as ammonia, nitrogen and phosphate.

Your discharge consent or authorisation from your environmental regulator will limit the number of fish held in cages to help minimise the impacts of fish waste.

Discharges to water or sewer

What you must do

If you use chemical treatments in cages, you must comply with any limits on chemical use included in your discharge consent or authorisation.

Good practice

You should use fallow periods, when fish are not held in cages, as they allow the lakebed to recover.

Use tarpaulins to minimise the amount of chemicals applied to the water.

You should take care to ensure that oil or fuel used for boats is not spilt onto land or into watercourses.

When you harvest fish, avoid spilling dead fish or blood into the water. Collect and remove all blood and fish waste. Take care not to spill any ice or water slurry into the water.

Frequently monitor cages for dead fish and remove them from the water as soon as possible

SEE ALSO: Preventing water pollution

Read about More ways to prevent water pollution on NetRegs

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