Why must water quality be controlled on a fish farm?

so the fish have enough oxygen and are not poisoned by waste. Dirty water also spreads disease.

Why are small fish kept apart from large fish?

To stop the large fish eating them. This is controlling predation.

What is a problem caused by keeping many fish close together?

Disease spreads easily. Parasites spread quickly too.

How is the growth rate of farmed fish improved over generations?

selective breeding. The fastest-growing fish are chosen as parents.

Why is uneaten food a problem on a fish farm?

It pollutes the water. It rots and uses up oxygen.

Fish farming · Edexcel IGCSE Biology 4BI1 revision

In plain words

Wild fish are being caught faster than they can breed. Fish farms raise them in cages or tanks instead, the way a farmer raises chickens. As with any crowded animals, the difficulties are food, disease and waste.

Three things to know

Fish are kept in cages or tanks where the water quality is controlled: it must be clean and have plenty of oxygen. Waste and uneaten food are removed.
They are fed small amounts often, so little food is wasted and the water stays clean. Fish of different sizes or species are kept apart so they don't eat each other.
Crowding lets disease and parasites spread, so fish are monitored and treated. Selective breeding gives fish that grow faster.

Tips and tricks

Reasons, not just methods: "fed little and often, so that less food is wasted and the water is not polluted".
Predation between fish of the same species is intraspecific; between different species it is interspecific.

5 questions, about 2 minutes.

It lands in your notebook with its questions as flashcards.

Fish farming: 5 questions and answers

These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.

Why must water quality be controlled on a fish farm?
- to change the colour of the fish
- so the fish have enough oxygen and are not poisoned by waste (the answer)
- to make the water warmer
- to stop the fish swimming
Dirty water also spreads disease.
Why are small fish kept apart from large fish?
- They eat different food.
- To stop the large fish eating them. (the answer)
- They need different water.
- To make counting easier.
This is controlling predation.
What is a problem caused by keeping many fish close together?
- They grow too fast.
- Disease spreads easily. (the answer)
- They need no food.
- They cannot breed.
Parasites spread quickly too.
How is the growth rate of farmed fish improved over generations?
- cloning
- selective breeding (the answer)
- vaccination
- pesticides
The fastest-growing fish are chosen as parents.
Why is uneaten food a problem on a fish farm?
- It attracts birds.
- It pollutes the water. (the answer)
- It makes fish thin.
- It kills weeds.
It rots and uses up oxygen.

5 questions

Tap an answer and you’ll see straight away whether it’s right, and why.

Worksheet

3 questions, 7 marks. Write your answers on paper, then check them.

Fish farming

Edexcel International GCSE Biology 4BI1 · 7 marks · papermunch.org

Name ______________________________ Date ______________

Describe three ways in which conditions on a fish farm are controlled to increase the yield of fish.[3]
Show answerHide answer
Any three: water quality is kept high (clean, with enough oxygen); waste is removed; fish are fed frequently in small amounts; fish of different sizes or species are separated to prevent predation; disease is controlled; selective breeding is used.
I got this one
Explain why disease spreads easily on a fish farm.[2]
Show answerHide answer
The fish are kept close together in large numbers, so pathogens and parasites pass easily from one to another.
I got this one
Explain why fish are fed small amounts frequently.[2]
Show answerHide answer
So that all the food is eaten: uneaten food would be wasted and would pollute the water.
I got this one

Answers: Fish farming

1. Any three: water quality is kept high (clean, with enough oxygen); waste is removed; fish are fed frequently in small amounts; fish of different sizes or species are separated to prevent predation; disease is controlled; selective breeding is used.
2. The fish are kept close together in large numbers, so pathogens and parasites pass easily from one to another.
3. So that all the food is eaten: uneaten food would be wasted and would pollute the water.