Fish Farming

This lesson covers:

  1. What fish farming is 
  2. How saltwater fish can be grown in sea cages, using the example of salmon farming  
  3. How freshwater fish can be grown in tanks or ponds, using the example of carp farming

Why do we farm fish?


Overfishing threatens the existence of many fish species in the wild. 

We use fish farming and sustainable fishing methods as an alternative way of sourcing fish that avoids overfishing.


  1. Fish farms are large enclosures or tanks designed to provide controlled environments for the growth of fish for human consumption. Obtaining our fish from fish farms allows wild fish stocks to recover.
  2. Opting for fish sourced from sustainable fisheries, in addition to fish farming, helps maintain fish stocks.

Seawater fish farming using sea cages


In fish farms, large numbers of fish are bred in small enclosures, and fed high-quality food in order to maximise growth and reproduction rates, in order to meet the high demand for fish.

Salmon farming in Scotland is an example of marine fish farming.

Diagram of seawater fish farming using sea cages showing salmon, sea lice, and wrasse.

Fish farming overview:

  1. The salmon are housed in sea cages to limit their movement, conserving energy for growth.
  2. The cages help prevent attacks from birds, seals, and other predators - called interspecific predation.
  3. Salmon receive a diet of high quality food pellets, designed to optimise their energy intake. This allows the fish to grow faster and larger.
  4. Juvenile fish are nurtured in specialised tanks to maximise their survival rate. By separating the young fish from the adults, we stop the adult fish from eating the young fish, preventing intraspecific predation.
  5. Diseases and parasites, such as sea lice, can be controlled with pesticides or biological pest control methods. For example, wrasses, small fish, are used to eat the lice off the salmon.
  6. Selective breeding is used to enhance productivity by creating less aggressive, faster-growing fish.

Tank farming


Aquatic species such as carp can also be farmed in controlled environments like ponds or indoor tanks.

Tank farming is particularly useful when the water needs to be tightly controlled.

Diagram showing tank farming of carp with clean water in, dirty water out, sensors, food, and filter.

Tank farming overview:

  1. Water conditions, including temperature, pH, and oxygen levels, are closely monitored and adjusted as needed.
  2. The amount and type of food supplied to the fish is regulated to ensure optimal growth.
  3. The water in the tanks is periodically drained and filtered to remove waste food and fish excrement, maintaining a healthy environment for the fish and minimising potential pollution when the water is discharged later.

In fish farms, what role do tanks or enclosures play in the cultivation of fish?

Decoration

Amphibious habitats

Fish feeding stations

Controlled environments

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What is a primary purpose of providing fish in fish farms with high-protein food?

To enhance their colouration

To encourage natural foraging behavior

To promote rapid growth for human consumption

To increase their size for aesthetic appeal

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What is the purpose of using wrasses in salmon farming?

To enhance productivity through selective breeding

To control diseases and parasites

To separate juvenile fish from adult fish

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