AQUACULTURE IN FRESHWATER

Course CodeBAG211
Fee CodeS3
Duration (approx)100 hours
QualificationStatement of Attainment

Grow Your Own Fish, and Improve Your Sustainability
 
Growing Fish or crustaceans (eg crayfish) to eat, can be a very achievable way to improve your food security on even a relatively small property.
 
Learning aquaculture involves getting an understanding of the broad principles as a foundation for understanding the husbandry of animals that live in water. This course is about getting that foundation for freshwater aquaculture.

Once you know how to manage and control water environments for a few different types of animals, you will then have a foundation that can be applied to growing any other fish or crustaceans you encounter in the future.

Lesson Structure

  1. Introduction: Scope and Nature of Freshwater Aquaculture
  2. Extensive or Intensive Production
  3. Choosing What Species to Farm
  4. Farming Trout
  5. Farming Barramundi, Freshwater Eels and Catfish
  6. Farming Bass
  7. Farming Crustaceans: Marron, Red Claw and the Yabbie
  8. Establishing up a Fish Farm
  9. Fish Foods and Feeding
  10. Harvesting and Health

Aims

  • Explain different aquaculture production systems.
  • Explain the cultural requirements of different types of fish suitable for aquaculture.
  • Explain cultural practices for freshwater crayfish.
  • Explain different factors affecting the vigour of animals in an aquaculture farm.
  • Explain methods, including feeding and harvesting, used to manage freshwater animal populations.
  • Develop informed management decisions for an aquaculture enterprise.

Water Quality Is Critical
 
If you want to do aquaculture, you need a good supply of water; and the quality of the water you use meeds to be maintained.
 
In some situations, you may have ample supply of water to keep washing fresh water through the system; but more often than not, some type of water treatment is needed, to clean water that is being then reused with the same animals. When fresh water is washing through the system; it is called an open system. When water is reused, it is called a closed system.
 
Unlike in the ocean, closed system pods or tanks cannot renew their water in a naturally occurring way; therefore, to maintain an aquarium clean, a good filtration system is essential, which will essentially avoid contamination, fish disease and possible deaths. Filters help remove the physical and chemical waste products solubilised in the water, such as wastes from excrements, uneaten food, fish respiration and/or fish deaths. 
 
There are 3 main types of filtration:
  1. Biological Filtration: Bacteria colonised in the gravel bed is responsible for biological filtration. This helps maintain a balanced nitrogen cycle by increasing the amount of surface area that nitrifying bacteria requires and by creating a regular flow of water over the colony of bacteria, which in turn allows them to metabolise the ammonia and nitrites by using the dissolved oxygen present in the water. For example: Under gravel Filter.
  2. Mechanical or Physical Filtration: Also known as “particulate filtration”. This process traps the particulate matter, such as decayed matter, uneaten food or other waste products, from the water column simulating a “sieve”. The finer the filter media, the smaller the particles that will be trapped and vice versa. For example: Sand Filters for large tanks or Foam Pads for smaller tanks.
  3. Chemical Filtration: This type of filtration is not essential for a healthy aquarium because its main purpose is to help maintain water clarity by removing specific toxins or certain medications that might have been introduced into the tank. Nevertheless, it is recommended when considering changing the chemical composition of the water. This process is mainly done by activated carbon, which is a cleaning resin that pulls dissolved organic pollutants, such as colours and odours, by “adsorbing” them. For example: Chemical Filters, Protein Foam Skimmers.
There is a variety of filters available that will suit different types of tanks their own specific requirements. These may be External or Internal:

 

External Power Filters
These are placed outside the tank, pond or aquarium and normally powered by a water pump. This type of filter pushes or pulls water from the tank into the filter media, where it collects wastes prior to returning the water back to the tank. They provide chemical and mechanical filtration, and some also provide biological filtration:
  • “Canisters” - normally used for tanks (freshwater or saltwater) that keeps a large number of fish. They provide a biological, chemical and mechanical type of filtration by removing the physical and soluble chemical waste products from the water in the tank. It may serve for “double filtration” purposes if the water is pumped from an under gravel filter into the canister.
  •  “Wet/Dry Filter” (also known as “Trickle Filter”) - usually positioned beneath a tank though they can be fitted above. When above, water passes through a series of perforated trays containing a filter material such as wool and sprinkles down into the tank. The filter material is kept wet but never fully submerged to allow aerobic bacteria to colonise it and act as a biological filter. If below, water passes out from beneath the aquarium and through the perforated trays containing the filter medium. Carbon dioxide is released and the aerobic bacteria filter out the toxins. The water passes to a sump which may contain further filtration compartments and from where it is pumped back into the system.
  • “Fluidized Bed Filter” (FBF) - these are biological filters which work on the basis of passing water upwards into a filter material of small sized particles whereby the filter becomes a fluid. Given the relatively large surface area of the small particles an abundance of aerobic bacteria on the surfaces are able to break down the waste products quickly and effectively.
  • “Sand Filters” - these are the most common type of fluidized bed filters.
Internal Power Filters
These are placed inside the tank, are powered by electricity and serve both as chemical and mechanical filtration:
  • “Under gravel Filters” - the under gravel filtration system consists of a porous plate located at the bottom of the tank, underneath the gravel, with one or more lift tubes that come up from the plate to the top of the tank. The particulate matter percolates through the gravel, where oxygen is pushed by air stones or by a water pump through the tubes recirculating clean water back in the tank. As an alternative to air stones or water pumps, a lift tube may also run with power heads mounted at the top of each tube. However, the gravel might get clogged with debris or accumulation of faecal matter throughout the time, decreasing flow rate and water quality. To avoid these problems, frequent water changes and gravel cleaning is required. If an under gravel filter is properly maintained, it provides an easy and reliable source of filtration for beginner aquarists. This type of filter will work as both biological and mechanical filtration.
  • “Corner Filters” (also known as “Box Filters”) - these serve as a filter by trapping debris and allowing the carbon to remove odours and discolouration to the water in the tank. Suitable for small stock aquariums, as well as for breeding purposes, as the sponge-like filter piece prevents the “fry” or small fish from entering the filter.

 

WHAT IS POSSIBLE AFTER THIS COURSE

With what you learn here, you will have a foundation to grow fish; whether that be on a small scale at home or on a hobby farm; working on someone else's farm or starting your own serious enterprise.

Freshwater aquaculture can be viable in a small garden, using as little as one large tank or pond perhaps only 3 metres across.

This is a relatively intensive form of farming; so even serious commercial operations don't usually require as much land as what you might need for farming larger land animals like sheep or cattle.

As with most things though; opportunities tend to reveal themselves as your awareness of the subject and the discipline grows. In doing this course, you will increasingly become aware of what is possible, and what is involved in each possibility -and that then equips you to decide what your next step will be.

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