This document summarizes common problems in aquaculture like algal blooms, muddy water, oxygen depletion, excess ammonia, and hydrogen sulfide formation. It discusses the causes of each problem and recommends preventive measures like regulating nutrient inputs, removing bottom mud, exchanging water, and applying lime to improve pond water quality and maximize fish production in a sustainable manner. Proper site selection and pond management through measures like drying and desilting ponds regularly can enhance the sustainability of aquaculture.

2. Muhammad Amjad
Ph.D. Scholar
mamjad5919@gmail.com
Department of Zoology
Government College University Faisalabad, Pakistan
Common Problems in Aquaculture and Their Preventive Measures

3. Introduction
Maintaining a good pond fish culture environment is crucial for growing healthy fish
Several technical difficulties may arise during fish culture with a possibility of large scale loss of
production.
High yield and profit in fish culture completely depends on proper management.
Improving culture efficiency
Achieving satisfactory production .

4. Introduction
1. Deep-Green Pond Water
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Muddy Pond Water
Red Layer on Pond Water
Oxygen Depletion
Excess Ammonia
Black Mud at Pond Bottom
Hydrogen Sulphide
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4
5
6
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5. Deep-Green Pond Water
Water color turns to deep green
Excessive algae in water
fish start grasping on the water surface and
sometimes face mass mortality.
Heavy fish loads
Excessive algae growth can
lead to a lack of dissolved
oxygen
Negative effects of
algae occur indirectly
when the population of algal cells
exceeds 100,000 cells/ ml, the
condition is termed as algal blooms.
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3
4
5
6
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6. Preventive measures
The best approach to algae control is to regulate nutrient inputs by moderate stocking and
feeding rates.
The major factor responsible for increased levels of phytoplankton in a water body is
phosphorous. Precipitate phosphorus by applying sources of iron, aluminium or calcium ions
Feed and fertilizer application should be stopped temporarily.
If necessary, water should be exchanged.
Lime @ 150-200 kg/ha should be applied.
Silver cap can be released for biological control.

7. Muddy pond water
Result of
Biological
Physical Environmental
How to determine cause of muddy water
Fill a glass jar with pond
water
Cover it with a lid
Allow it to sit undisturbed for
one week
If the water is still muddy
after one week
Cause is physical
layer of sediment in the
bottom of the jar
Environmental or biological

8. Effect of muddy water
can hinder the feeding
ability of fish
Sunlight penetration is
reduced
DO capacity is reduced
Fish gill can be
damaged
phytoplankton growth is
reduced
Fish growth is reduced

9. Prevent surface runoff water
from entering to the pond.
Limit the access of cattle, buffalo
etc
Do not stock large number of
bottom dwelling fish
Apply of alum @ 15-25 mg (150-
275 kg/ha)
Apply Gypsum @ (1000-3000
kg/ha
Reclamation

10. • The red layer on the water surface forms due
to excess iron content or Euglenoid algae in
pond water.
• This results in shortage of food and oxygen in
water.
• The red layer floating on the pond surface can
be pulled and picked up using a rope made by
coiling rice straw or banana leaves.
• Spreading urea 2- 3 times @ 25 -30 kg/ha on
the pond surface may give good result.
• Alum @ 25-30 kg/ ha can be applied to the
water to reduce the red bloom.
Red layer on pond
Preventive measures

11. Black Mud at Pond Bottom
Soil of the bottom turns to dark
and smelly
Due to buildup of extra feed and
organic matter at the pond bottom,
Problem can be severe in a pond where
fish culture is going on for long time
fish may face mass mortality due to
the toxic gases at the bottom.

12. Preventive measures
Before fish stocking, excessive bottom mud should be removed.
If mass mortality of fish fry is observed during culture period:
Water should be exchanged right away and fish density should be
reduced.
Avoid manure application.
Apply lime and allow maximum sunlight.
Apply artificial feed

13. Oxygen depletion
• A commonly encounter problem by the fish farmers.
• Generally during very early in the morning, fish
start floating and grasping on the water surface.
• It happens due to the shortage of dissolved oxygen
in water.
• If shortage of oxygen is very high and long lasting,
then fish start to die and dead fish have their mouths
wide open.
• Large fish may die first, but all sizes of fish are
usually affected.

14. Causes
 Dense plankton blooms or dense stands of pond weeds.
 Several days of cloudy weather that reduces plant oxygen production.
 High temperatures, which decrease the solubility of oxygen in water and increase oxygen consumption by plants and
animals.
 Sudden die-off of plants or algae, especially associated with herbicide use.
 Unusual weather patterns, such as storm fronts and heavy cold rain.
 Overstocking fish, excessive fertilization, or high feeding rates.
 Decomposition of organic matter, leaves and branches of trees in water
 Excessive application of wet cow dung in pond
 Excessive turbidity in water
 High iron content in soil

15. Preventive measures
1. Agitate the pond water by splashing, swimming, beating with bamboo
poles, re-pumping with the help of a pump or using a mechanical
churner/aerator.
2. Add freshwater in the pond by pumping it from nearby sources.
3. Apply lime @ 150-200 kg/ha and rake up the bottom
4. Water pH should be measured after rain.
5. Quick lime / dolomite 20-25 kg/ha should be used.

16. Excess Ammonia
1. Ammonia is produced by excretion of fishes, crustaceans and other fauna
2. Microbial decomposition of organic materials
3. Ammonium fertilizers
4. Supplementary feed etc
5. Ammonia is more toxic when dissolved oxygen concentration in fish ponds is low;
6. Toxicity of ammonia decreases with low pH and increased CO2 concentration in
fish ponds;
7. Toxicity of ammonia decreases slightly by high concentration of calcium.

17. Preventive measures
• Stop fertilizer and feed application after reducing stocking density.
• Stop using lime and control pH, as higher pH favors ammonia toxicity
to fish.
• Exchange 30 – 50 % of water, if possible.
• At the preliminary stage table salt @ 80-100 kg /ha water can be
applied.
• Zeolite can be applied to absorb ammonia.
• Provide aeration in pond, as it will increase dissolved oxygen
concentration and decrease pH; thereby reducing ammonia toxicity.
Ammonia

18. Hydrogen Sulphide
• Concentration of H2S in water creates stress to fish
• Hydrogen sulphide is produced by chemical reduction of organic
matter that accumulates and forms a thick layer of organic deposit
at the bottom.
Preventive measures
Frequently exchange pond water to prevent building-up of hydrogen
sulphide in pond.
Apply lime to increase pH of water, as toxicity of hydrogen sulphide
decreases with increasing Ph.

19. Larger Aquatic Plants in Pond
• Larger aquatic plants or macrophytes include pondweed and
milfoil
• They are undesirable in fish-ponds because of the reasons
Interfere with fish management such as feeding and harvesting;
• Compete with plankton for nutrients;
• Provide shelter for undesirable fish;
• Contribute to oxygen depletion and high ammonia levels when they
decompose;
• Contribute to water loss through evapotranspiration.

20. • Drying and desilting of ponds every 1-2 years;
• Mechanical harvesting;
• Increasing phytoplankton turbidity (fertilizing);
• Herbicides application.
Preventive measures

21. • Drying and desilting of ponds every 1-2
years;
• Mechanical harvesting;
• Increasing phytoplankton turbidity
(fertilizing);
• Herbicides application.
Preventive measures

22. select proper site with good soil and high quality water and
maintain moderate levels of prawn and fish production.
Proper pond management is the key to sustainability in
aquaculture
Enhancing sustainability of pond aquaculture can improve soil and
water quality in ponds and reduce the volume and pollution
potential of pond effluents.
Proper procedures for pond management will improve environmental
conditions, sustainability and profits.
Conclusion