Fish Husbandry

Question 1

How would you describe the distribution of fish?

Answer 1

Vertical, found all over the world

Question 2

What is present in a fish’s blood to allow them to deal with sub-zero temperature?

Answer 2

Antifreeze

Question 3

What are the 3 water salinity types that a fish could be found in?

Answer 3

• Freshwater
• Brackish (slightly salty e.g. rivers)
• Marine

Question 4

How can oxygen requirements vary between fish species?

Answer 4

• some need cold, O2-rich streams
• some survive in high altitude warm springs
• some survive 3 months without O2 in ice-covered ponds and lakes

Question 5

What are the main husbandry requirements that need to be considered when keeping fish?

Answer 5

• Oxygen
• Temperature tolerance
• Salinity
• pH requirements
• Space/size of tank
• Behaviour/aggression
• Health

Question 6

What are 4 husbandry requirements of Rainbow trout?

Answer 6

• Freshwater
• Optimum temp 18 degrees
• Benefit from fast flowing water
• Aggressive predator

Question 7

Give 4 husbandry requirements of Sea bass

Answer 7

• Marnie
• pH 7.6-8.4
• Optimal temp = 12 degrees
• Social and fast growing

Question 8

Which problems mean that filtration is vital for fish health in a tank?

Answer 8

• Fish release ammonia as metabolic waste, this is very toxic
• Faeces and other solid waste decays in the water
• Clouds the water

Question 9

What are the 3 sequential sections of a filtration system?

Answer 9

• Mechanical
• Biological
• Chemical

Question 10

Which 4 features make up mechanical filtration?

Answer 10

• Filter mats
• Swirl filters
• Sand filters
• Brushes

Question 11

What is the aim of biological filtration?

Answer 11

Encourage the growth of beneficial autotrophic bacteria which will breakdown the toxic nitrogenous waste via nitrification

Question 12

In biological filtration, what is ammonia broken down into? Which bacteria are involved in this process?

Answer 12

Ammonia -> (Nitrosomonas) -> Nitrite -> (Nitrobacter) -> Nitrate

Question 13

What is the aim of chemical filtration?

Answer 13

To remove/adsorb specific undesirable substances from the water

Question 14

Which 3 chemicals are used in chemical filtration?

Answer 14

1. Carbon granules to remove ‘colour’ from the water
2. Zeolite can remove ammonia
3. Phosphate removing granules prevent algae growth

Question 15

What are the 3 approaches of fish management? Which is the most intense?

Answer 15

Open
Semi-closed
Closed = Most intense

Question 16

Describe an open fish system

Answer 16

Caged environments in e.g. rivers, lakes estuaries, open sea.
Lack intensive water quality management, rely on the natural system to maintain water quality.
Can have very low or very high densities of fish.
Sea bass, salmon

Question 17

Describe a semi-closed system

Answer 17

Flow-through or once-through systems, or raceways.
Inland aquaculture.
Inlet and outlet, fast continuous water flow
Allows high densities of fish

Question 18

Describe a closed system

Answer 18

Recirculating aquaculture systems RAS
Water re-conditioned and recirculated
Marine and freshwater
High fish densities
Minimal water and land use
Highly controlled growth conditions
Needs very efficient bio-filtration
Expensive to set up and maintain
Needs highly trained staff

Question 19

What are some features of an ornamental tank set up?

Answer 19

• Filter
• Food
• Enrichment
• Oxygenator
• Thermostat
• Timed lights