Environmental stress Diseases in finfish and shellfish

Here is my presentation on the topic environmental stress diseases in finfishes and shellfishes covering the most important topics in single frame

1. Environmental stress Diseases in fin fish and shell fish
Presentation by
Dinesh pakalapati
Roll no –16
MSC Marine Biology
DISEASE AND HEALTH MANAGEMENT IN AQUACULTURE -SEM II
~ VIKRAMA SIMHAPURI UNIVERSITY

2. What is environmental stress diseases
●Environmental stress diseases in fishes and shellfishes occur when changes in their surroundings negatively
affect their health. These stresses can be caused by factors like poor water quality, temperature
fluctuations, low oxygen levels, pollution, and overcrowding. When fish and shellfish experience stress,
their immune systems weaken, making them more vulnerable to infections and diseases.
●In aquaculture and natural habitats, environmental stress can lead to mass fish deaths, reduced growth,
and economic losses. Understanding these stressors and how to manage them is essential for maintaining
healthy fish populations and sustainable fisheries. In this presentation, we will discuss the major
environmental stress factors, their effects on fish health, and ways to prevent and manage these issues.

3. Why Environmental Stress Diseases are Important in Aquaculture
Environmental
stress Diseases
Prevents
Mass
Mortalities
Improves
Growth and
Production
Reduces
Disease
Outbreaks
Ensures
Sustainable
Aquaculture
Economic
Benefits
Maintains
Food Safety
and Quality

4. Introduction
01
Environmental stress diseases in fin fishes occur when unfavorable
conditions in their habitat weaken their immune systems, making
them vulnerable to infections and poor health. Common stress
factors include dissolved oxygen levels, pH imbalances,
temperature fluctuations, and gas-related issues. Understanding
these stressors and their treatments is essential for successful
aquaculture and fish farming.

5. Major Environmental Stress Factors and
Their Effects!!!

6. 1. Dissolved Oxygen (DO) Deficiency
"DO" refers toDissolved Oxygen, which is the amount of oxygen gas (O2)
that is dissolved in water, and is vital for the survival, growth, and health of
aquatic organisms.
dissolved oxygen (DO) is primarily formedthrough photosynthesis by
aquatic plants and algae, and by diffusionfrom the atmosphere.

8. Dissolved Oxygen (DO) Deficiency
•Cause:Overcrowding, high organic waste, high temperatures, and algal blooms.
•Effects: Fish struggle to breathe, become sluggish, and may die due to asphyxiation.
•Symptoms:Gasping at the surface, erratic swimming, and slow growth.
•Treatment:
Use aeratorsor paddle wheelsto increase oxygen levels.
Reduce stocking density.
Maintain DO levels above 5 mg/Lfor healthy fish.

9. Asphyxiation in shrimps
Asphyxiation in finfishes Sluggish behavior in fishes

10. DO METER

11. 2. pH Imbalance (Acidosis & Alkalosis Problems)
pH isa measure of water acidity that's important in aquaculture because it affects
fish health and survival.
The pH scalemeasures how acidic or basic a substance is, ranging from 0 to 14.
How is pH measured?
Using a pH meter, which provides a numerical value
Using litmus paper, which changes colour depending on whether the substance is acidic or basic
Comparing the colour of an indicator to a comparison chart
Factors that affect pH -
Temperature: As the temperature increases, the pH of pure water decreases
Chemicals: Chemicals in the water can affect the pH
Rain: Rain that combines with sulphur dioxide or nitrogen oxides from power plants and automobiles becomes more acidic

12. 2. pH Imbalance (Acidosis & Alkalosis Problems)
•Acidosis (Low pH < 6.5):Causes excessive mucus secretion, gill damage, and stress.
•Alkalosis (High pH > 8.5):Leads to skin damage, poor digestion, and reduced growth.
Treatment:
For low pH, add agricultural lime (Calcium Carbonate) at 500 kg/hato stabilize
acidity.
For high pH, use organic acids like Gypsum CaSO4·2H2Oor alum at 25-50 mg/L
to lower pH.

13. pH meter
pH paper

14. pH deficiency in fishes
pH deficiency in shrimps

15. 3. Gas Bubble Disease (Supersaturation of Gases, Mainly Nitrogen)
•Occurs when water contains excess dissolved gases, forming bubbles in fish
tissues.
•Causes bulging eyes, swollen belly, and internal bleeding.
•Mortality
Treatment:
Reduce turbulence in water and use degassing columnsin recirculating
aquaculture systems (RAS).
Avoid overuse of pressurized aeration systems.

16. Gas Bubble Disease (Supersaturation of Gases, Mainly Nitrogen)
●In aquaculture, dissolved gas supersaturation (DGS)occurs when the
partial pressures of atmospheric gases in water exceed their
respective pressures in the atmosphere, potentially leading to gas
bubble trauma (GBT) in fish.
●DGS happens when the amount of dissolved gases (like oxygen,
nitrogen, and carbon dioxide) in water is higher than what the water
can normally hold at a given temperature and pressure.

17. D
Gas bubbles in muscle tissues
Internal bleeding

18. 4. Temperature Disturbances
•Sudden temperature fluctuationscause thermal stress, reducing immunity.
•Cold stress (<15°C)slows down metabolism, while heat stress (>30°C)leads to oxygen depletion.
Treatment:
•Maintain optimal temperature ranges for species:
•Tilapia: 25-30°C
•Shrimp: 26-32°C
•Catfish: 24-28°C
○Use shade nets or deep pondsto buffer against extreme temperatures.

19. High depth ponds
Shade nets

20. 5. Ammonia and Nitrite Toxicity
High ammonia (>0.1 mg/L) and nitrites (>0.5 mg/L) damage fish gills and blood,
causing stress and disease.
Signs include red gills, erratic swimming, and increased mortality.
Treatment:
Reduce ammonia by applying Zeolite at 10-20 g/m³to absorb toxic compounds.
Add probiotics (Bacillus spp.) at 1-2 g/kg feedto improve nitrogen cycling.

21. Red gills
Mass mortality

22. 6. Overcrowding and Handling Stress
•Causes aggression, reduced oxygen availability, and increased
disease risks.
Treatment:
•Maintain ideal stocking densities:
•Shrimp: 50-100 PL/m²
•Catfish: 5-10 fish/m³
•Use antistress vitamins (Vitamin C at 500 mg/kg feed)to
enhance immunity.

23. Over crowding
Handling stress of over
crowded bio floc

24. 7. Harmful Algal Blooms (HABs) and Toxins
•Blooms of toxic algae cause poisoning in shellfish and oxygen depletion in
ponds.
Treatment:
•Use copper sulphate (0.2 mg/L)or natural clay to remove algae.
•Regular water exchange prevents bloom formation.

25. HAB
HAB

26. Common Diseases Caused by
Environmental Stress and
Their Treatments

27. Disease Causes Symptoms Treatment & Dosage
Gill Rot (Bacterial Gill
Disease)
Low DO, ammonia, pH
imbalance
Labored breathing,
swollen gills
Potassium Permanganate (2-4
mg/L) or Oxytetracycline (50
mg/kg feed for 7 days)
White Spot Disease
(Ich)
Temperature stress
White cysts on skin,
flashing behavior
Formalin (25 mg/L for 1
hour) or Salt bath (5 ppt
for 10 mins)
Vibriosis (Shrimp &
Fish)
Salinity changes,
overcrowding
Red lesions, tail rot, high
mortality
Oxytetracycline (100
mg/kg feed for 5-7
days) or Probiotics
Shell Disease (Crabs &
Shrimp)
Poor water quality,
bacterial infection
Dark spots, soft shells
Lime treatment and
proper water exchange

28. Prevention and Management
Strategies

29. 1.Regular Water Quality Monitoring
•Check DO, pH, ammonia, and nitritesusing test
kits.
•Maintain water exchange and filtration in ponds.
2.Use of Aeration and Water Circulation
•Install aeratorsto maintain dissolved oxygen levels.
3.Stocking Density Control
•Avoid overstocking to reduce stress and disease risks.
4.Proper Nutrition and Probiotics
•Use Vitamin C, Vitamin E, and probioticsto
improve fish immunity.
5.Biosecurity Measures
•Quarantinenew stock before introducing them to
ponds.
•Disinfect nets and equipment regularly.

30. Conclusion
Environmental stress diseases in
fin fishes and shellfishes are a
major challenge in aquaculture.
Factors like poor water quality,
temperature fluctuations, and
pollution can severely impact
health and productivity. By
maintaining good environmental
conditions, using proper
treatments, and following
preventive measures, farmers
can ensure healthy fish stocks
and sustainable aquaculture
production.

31. [email protected]
Thanks!
@fishcos_
@Dinesh pakalapati