Aquaponics Technician Certification
Exam 2025\2026
answers and rationale
1. Which of the following is a primary component of an aquaponics
system?
a) Soil beds
b) Fish tanks
c) Wind turbines
d) Drip irrigation
b) Fish tanks
Rationale: Fish tanks are essential in aquaponics for providing
nutrients through fish waste.
2. What is the main purpose of a biofilter in an aquaponics system?
a) To remove solid waste
b) To convert ammonia to nitrates
c) To circulate water
d) To provide oxygen
b) To convert ammonia to nitrates
Rationale: Biofilters host nitrifying bacteria that convert toxic
ammonia from fish waste into nitrates, which plants use.
3. Which nutrient is most critical for plant growth in aquaponics?
a) Nitrogen
b) Potassium
c) Phosphorus
d) Calcium
a) Nitrogen
, Rationale: Nitrogen, in the form of nitrates, is vital for
vegetative growth.
4. What is the ideal pH range for most aquaponics systems?
a) 4.5–5.5
b) 5.5–6.0
c) 6.8–7.0
d) 7.5–8.0
c) 6.8–7.0
Rationale: A slightly neutral pH supports both plant nutrient
uptake and fish health.
5. Which fish species is commonly used in aquaponics due to its
hardiness?
a) Salmon
b) Tilapia
c) Trout
d) Catfish
b) Tilapia
Rationale: Tilapia tolerates a wide range of water conditions and
grows quickly, making it ideal for aquaponics.
6. What is the role of solids removal in aquaponics?
a) Increase water temperature
b) Prevent bacterial growth
c) Remove uneaten feed and waste
d) Increase oxygen levels
c) Remove uneaten feed and waste
Rationale: Removing solids prevents ammonia spikes and
maintains water quality.
7. Which component measures water temperature in an aquaponics
system?
, a) Thermometer
b) Refractometer
c) pH meter
d) Flow meter
a) Thermometer
Rationale: Maintaining appropriate water temperature is critical
for fish metabolism and plant growth.
8. Which nitrogen compound is toxic to fish at high concentrations?
a) Nitrates
b) Nitrites
c) Ammonia
d) Phosphates
c) Ammonia
Rationale: Ammonia buildup can harm or kill fish if not
converted by bacteria in the biofilter.
9. What is the main benefit of floating raft systems in aquaponics?
a) Reduced water usage
b) Faster fish growth
c) Easier plant harvesting
d) Lower initial cost
a) Reduced water usage
Rationale: Floating raft systems maximize water efficiency by
keeping roots submerged in a recirculating nutrient solution.
10. What does DO stand for in aquaponics water quality testing?
a) Dissolved Oxygen
b) Density Output
c) Dynamic Organics
d) Direct Oxidation
a) Dissolved Oxygen
, Rationale: Adequate dissolved oxygen is essential for fish
respiration and beneficial bacterial activity.
11. Which method can prevent algae growth in aquaponics
systems?
a) Reduce water circulation
b) Block sunlight from the water
c) Increase nutrient feed
d) Reduce fish stocking
b) Block sunlight from the water
Rationale: Algae require light to grow, so preventing light
exposure inhibits their proliferation.
12. Which of the following plants is well-suited for NFT (nutrient
film technique) systems?
a) Potatoes
b) Lettuce
c) Carrots
d) Tomatoes
b) Lettuce
Rationale: Lettuce thrives in shallow nutrient films with constant
water flow.
13. What is the recommended stocking density for tilapia in
aquaponics?
a) 1 fish per 10 liters
b) 1 fish per 20 liters
c) 1 fish per 50 liters
d) 1 fish per 100 liters
b) 1 fish per 20 liters
Rationale: This density allows sufficient oxygen, reduces stress,
and optimizes growth.
Exam 2025\2026
answers and rationale
1. Which of the following is a primary component of an aquaponics
system?
a) Soil beds
b) Fish tanks
c) Wind turbines
d) Drip irrigation
b) Fish tanks
Rationale: Fish tanks are essential in aquaponics for providing
nutrients through fish waste.
2. What is the main purpose of a biofilter in an aquaponics system?
a) To remove solid waste
b) To convert ammonia to nitrates
c) To circulate water
d) To provide oxygen
b) To convert ammonia to nitrates
Rationale: Biofilters host nitrifying bacteria that convert toxic
ammonia from fish waste into nitrates, which plants use.
3. Which nutrient is most critical for plant growth in aquaponics?
a) Nitrogen
b) Potassium
c) Phosphorus
d) Calcium
a) Nitrogen
, Rationale: Nitrogen, in the form of nitrates, is vital for
vegetative growth.
4. What is the ideal pH range for most aquaponics systems?
a) 4.5–5.5
b) 5.5–6.0
c) 6.8–7.0
d) 7.5–8.0
c) 6.8–7.0
Rationale: A slightly neutral pH supports both plant nutrient
uptake and fish health.
5. Which fish species is commonly used in aquaponics due to its
hardiness?
a) Salmon
b) Tilapia
c) Trout
d) Catfish
b) Tilapia
Rationale: Tilapia tolerates a wide range of water conditions and
grows quickly, making it ideal for aquaponics.
6. What is the role of solids removal in aquaponics?
a) Increase water temperature
b) Prevent bacterial growth
c) Remove uneaten feed and waste
d) Increase oxygen levels
c) Remove uneaten feed and waste
Rationale: Removing solids prevents ammonia spikes and
maintains water quality.
7. Which component measures water temperature in an aquaponics
system?
, a) Thermometer
b) Refractometer
c) pH meter
d) Flow meter
a) Thermometer
Rationale: Maintaining appropriate water temperature is critical
for fish metabolism and plant growth.
8. Which nitrogen compound is toxic to fish at high concentrations?
a) Nitrates
b) Nitrites
c) Ammonia
d) Phosphates
c) Ammonia
Rationale: Ammonia buildup can harm or kill fish if not
converted by bacteria in the biofilter.
9. What is the main benefit of floating raft systems in aquaponics?
a) Reduced water usage
b) Faster fish growth
c) Easier plant harvesting
d) Lower initial cost
a) Reduced water usage
Rationale: Floating raft systems maximize water efficiency by
keeping roots submerged in a recirculating nutrient solution.
10. What does DO stand for in aquaponics water quality testing?
a) Dissolved Oxygen
b) Density Output
c) Dynamic Organics
d) Direct Oxidation
a) Dissolved Oxygen
, Rationale: Adequate dissolved oxygen is essential for fish
respiration and beneficial bacterial activity.
11. Which method can prevent algae growth in aquaponics
systems?
a) Reduce water circulation
b) Block sunlight from the water
c) Increase nutrient feed
d) Reduce fish stocking
b) Block sunlight from the water
Rationale: Algae require light to grow, so preventing light
exposure inhibits their proliferation.
12. Which of the following plants is well-suited for NFT (nutrient
film technique) systems?
a) Potatoes
b) Lettuce
c) Carrots
d) Tomatoes
b) Lettuce
Rationale: Lettuce thrives in shallow nutrient films with constant
water flow.
13. What is the recommended stocking density for tilapia in
aquaponics?
a) 1 fish per 10 liters
b) 1 fish per 20 liters
c) 1 fish per 50 liters
d) 1 fish per 100 liters
b) 1 fish per 20 liters
Rationale: This density allows sufficient oxygen, reduces stress,
and optimizes growth.
