WorksheetsYêu cầu chính của môi trường nuôi thuỷ sản
Total questions: 30
Worksheet time: 15mins
Which water temperature range best supports warm-water fish growth and survival in aquaculture?
About 13 to 18 degrees Celsius
About 20 to 24 degrees Celsius
About 25 to 30 degrees Celsius
About 32 to 36 degrees Celsius
Which water color and transparency indicate strong phytoplankton growth suitable for freshwater fish ponds?
Deep blue with 60 cm clarity
Clear colorless with 80 cm clarity
Light green with 20–30 cm clarity
Brown-black with 5 cm clarity
What is the minimum dissolved oxygen level generally suitable for most cultured aquatic animals?
Below 2 mg/L
Above 10 mg/L
Above 5 mg/L
Around 3 mg/L
Which statement about diurnal variation of dissolved oxygen in ponds is most accurate?
Constant all day due to aeration
Lowest at noon due to heating
Lowest before dawn after night respiration
Highest at midnight from wind mixing
Which pH range typically supports healthy growth of most cultured aquatic animals?
4.5 to 5.0
5.5 to 6.5
6.5 to 8.5
8.8 to 10.0
At what maximum ammonia concentration (as NH3/NH4+) should a well-managed pond be maintained for good animal growth?
Below 0.01 mg/L
Below 0.1 mg/L
Below 0.5 mg/L
Below 1.0 mg/L
Which species group is best described as euryhaline with tolerance to 0–35% salinity?
Cold-water trout species
Common carp only
Freshwater snails exclusively
White shrimp and some tilapia
Which device or method is appropriate for quick, on-site measurement of pH in aquaculture ponds?
Gas chromatograph
Electronic pH meter or pH paper
Colorimeter for turbidity
Flame photometer
Which role do phytoplankton primarily play in pond ecosystems for aquaculture?
Provide dissolved oxygen and food base
Consume oxygen and raise ammonia
Neutralize heavy metals directly
Increase salinity through precipitation
Which combination best characterizes a balanced pond biota for stable water quality?
Absence of algae and detritivores
Dominant phytoplankton and suitable zooplankton
Only benthic worms without microalgae
High harmful bacteria, low zooplankton
Which natural factor most directly sets suitable species and stocking seasons in aquaculture areas?
Local soil texture and clay content
Regional weather and climate patterns
Watershed size and catchment shape
Average farm machinery availability
What characteristic of the water source is critical for sustaining aquaculture throughout the year?
High turbidity and suspended solids
Strong tidal mixing near outlets
Low conductivity in dry seasons
Consistent flow and appropriate quality
In earthen ponds, why can soil characteristics influence water quality?
They control sun exposure and wind
They drive direct exchange with bottom
They limit algae photosynthesis only
They ensure constant aeration rates
During feeding, approximately what portion of nutrients can become waste accumulating in pond water and bottom?
About ten percent of nutrients
About seventy percent of nutrients
About thirty percent of nutrients
About ninety percent of nutrients
Which management technology is aimed at reducing organic load by microbial conversion within culture systems?
Biofloc systems for in-situ treatment
Ozonation for rapid oxidation
Sand filtration for clear water
UV irradiation for pathogen kill
A pond shows overly dense algal blooms and dark water. What action best addresses this condition first?
Stop aeration during daytime
Add high-protein feed twice daily
Apply copper sulphate immediately
Increase daily clean water exchange
What is a key role of environmental management in aquaculture operations?
Guarantee maximum harvest weights
Keep pH fixed at exactly 7.00
Maintain suitable water quality ranges
Eliminate all disease organisms
Which practice helps prevent pollution when preparing water supplies before stocking?
Ensure reliable quantity and quality
Use single, shallow intake ditch
Reduce settling pond area below 5%
Divert drainage through fish cages
Which is a primary role of environmental management in aquaculture systems?
Select safe water sources to reduce toxins
Guarantee zero disease without monitoring
Increase feed conversion ratio in all species
Eliminate all microorganisms in pond water
Before stocking, which requirement best describes a water supply for a farm?
Continuous provision with controllable flow
Occasional rain-fed inflow only
Intermittent supply via manual buckets
Seasonal floodwater without treatment
What is a key design requirement for water storage ponds at a farm site?
Depth equal to culture ponds at all times
Exactly the same depth as grow-out ponds
Shallower than culture ponds by 1 meter
Depth higher than culture ponds by 0.3–0.5 m
If pond water becomes too turbid and dark from algal blooms, which action is most appropriate?
Stop aeration to calm the water surface
Increase shading to keep water stagnant
Remove excess organic waste and change 10–20% water daily
Add high-protein feed to settle particles
Which practical method helps control water temperature during extreme sunlight?
Add salt to raise boiling point
Increase feeding frequency
Use shading nets over ponds
Reduce aeration at night
To manage dissolved oxygen effectively, what practice is recommended in most farms?
Use aeration once per week schedule
Operate aerators mainly at night and dawn
Turn off aeration during algae growth
Aerate only during heavy rain events
When pond pH is too low, which corrective measure is suitable?
Add high doses of copper sulphate
Increase feeding with oily pellets
Apply agricultural lime or baking soda
Introduce freshwater prawns immediately
Salinity rises after drought; what is the best management option for grow-out ponds?
Dilute with freshwater or add rainwater
Increase aeration to strip salt
Add more organic manure to buffer
Raise pH using alum to neutralize
Which step is essential before filling a pond for aquaculture to stabilize water quality?
Introduce nitrifying bacteria first
Use only mechanical aeration devices
Add fish immediately without preparation
Apply lime and dry the pond bottom
A farm detects disease in stock. What is the appropriate handling of wastewater to prevent spread?
Release water to nearby streams directly
Increase feeding rate to dilute pathogens
Reuse wastewater for domestic purposes
Treat effluent per regulations before discharge
A pond shows high ammonia after feeding. Which biotechnology approach best reduces ammonia toxicity?
Add chlorine disinfectant at high doses
Promote nitrifying bacteria like Nitrosomonas
Stop all aeration to limit oxidation
Introduce heterotrophic yeasts only
Solid sludge (bùn thải) accumulates after harvest. What is a suitable management action?
Burn sludge to eliminate moisture
Pump directly into rivers untreated
Leave in pond to settle permanently
Remove and use in agricultural areas
