1. Understanding the Environmental Requirements for Fish

2. Understanding the Environmental Requirements for Fish
Take a drink of water.
How good does it taste?
How important is water to your life?
How important is water to fish?

3. What factors affect water quality?
Water is a simple compound consisting of 2 parts hydrogen and 1 part oxygen.
Water and its quality are very important in fish production
Water quality has 3 characteristics
chemical characteristics
physical characteristics
biological characteristics

4. Chemical characteristics
Water chemistry - many dissolved molecules combined in the water.
Common substances in water:
Dissolved oxygen
Nitrogen
Hydrogen sulfide
Carbon dioxide
Iron

5. Chemical characteristics
pH and salinity affect water chemistry pH
Measure of the water’s acidity or alkalinity.
Salinity
Amount of dissolved salt in the water.

6. Physical characteristics
Temperature
Determines physical characteristics
Physical characteristics of water
Solid
Liquid
Gas
Fish have a specific range of temperatures that they can survive

7. Water biology Water biology Plankton
All of the living and non-living organisms in the water
From the large aquatic plants to the small microscopic organisms
Plankton
Tiny plants and animals that float in the water

8. Plankton Types of plankton Phytoplankton Zooplankton
Algae plankton which produce oxygen through photosynthesis
Zooplankton
Microscopic animal life that is often used as food by many fish

9. Water biology
Biomass
All living organisms in a given location

10. What is water oxygenation?
Fish rely on dissolved oxygen in water to sustain their life functions.
The amount of available oxygen is a limiting environmental factor.
When oxygen is limited, oxygen can be added.
This process is called oxygenation.

11. What is water oxygenation?
One source of oxygen is from the air above the water.
This process of obtaining oxygen from air above water is called aeration.

12. Methods of aeration Splashing Pumping air or oxygen into water
Water is added to system
Water splashed against concrete or something similar
Allows more water molecules to come into contact with air molecules
Pumping air or oxygen into water
Allows oxygen molecules to come in contact with water molecules
Allows oxygen to become dissolved in the water
Commonly seen in fish tanks

13. Methods of aeration Spraying water in air
Use of a fountain or a paddle wheel.
Water is sprayed into air causing it to come into contact with oxygen.
Water catches this oxygen and brings back down into water.

14. Methods of aeration Using chemicals
Potassium permanganate added to ponds causing a chemical reaction that releases oxygen.
Common method of using chemicals is fertilizing the pond.
This allows aquatic plants to grow increasing photosynthesis.

15. What are the effects of nitrogen in water?
Nitrogen is an abundant element in the environment.
Nitrogen circulates through the atmosphere, soil, water, animals, and plants.
This circulation is known as the nitrogen cycle.
Excessive nitrogen in water can be toxic to fish.
Highly intensive fish production systems, nitrogen can be a problem.

17. Where does the nitrogen come from?
Organic wastes in the water causes excessive nitrogen in fish production.
Organic material can be manure from fish or uneaten feed.
As this material decomposes, ammonia is released.
Ammonia converted to nitrites.
Ammonia and nitrites both harmful to fish.

18. Ammonia toxicity Ammonia toxicity
Level of ammonia that can cause harm
High levels of nitrite in the water will prohibit blood of the fish from effectively carrying oxygen.

19. Factors making ammonia more toxic
Ammonia toxicity
Factors making ammonia more toxic
Increasing temperatures
pH becomes more alkaline
Dissolved oxygen decreases
Carbon dioxide increases
Salinity decreases

20. Preventing nitrogen problems
Intensive fish production cause nitrogen levels to change quickly.
Test nitrogen levels regularly.
Care should be taken to prevent over feeding of the fish.
Design system to allow for proper water flow to remove waste from system.

21. What are the effects of other common compounds found in water?
Phosphorus, chlorine, and heavy metals may cause problems with water quality.
Phosphorus
Usually attributed to wastes entering water.
In combination with nitrogen can cause excessive nutrients in water.
This is called eutrophication.
This leads to algae blooms causing a decrease in oxygen in water.

22. What are the effects of other common compounds found in water?
Chlorine
Usually attributed to municipal chlorinated water entering the system.
Can cause problems for some species of fish.
To eliminate chlorine
Water needs to be de-chlorinated by aging or chemical treatments.

23. What are the effects of other common compounds found in water?
Heavy metals
Lead and mercury.
Attributed to water pollution from manufacturing or illegal dumping.
May not kill the fish, however absorbed into fish and cause problems for humans consuming the fish.
Test water for heavy metals.