Types of Aquaculture

Systems

What are the types of aquaculture systems?•There are 5 types of aquaculture systems• Pond Culture• Canal Culture• Cage Culture• Raceway Culture• Recirculating Systems.

Pond Culture

•Ponds are earthen enclosures that hold water. •Most common way to raise fish.• Easy design and low construction costs.

•Need large areas of land.

Canal Culture

•Irrigation canals are also used to raise fish. •In areas where water is scarce, it is good to have multiple ways to use water. •Divided into sections by nets or screens •As long as no chemicals are placed into the canals, they can be a great place to raise fish.

Cage Culture•Cages are floating structure designed to contain fish. • Common in large bodies of water such as

lakes and oceans.

•Allow water and feed to freely float through them and fish wastes to move away •Allow for easy capture of fish •Cages come in various sizes and shapes.

Raceway Culture

•Raceways are long narrow structures where water constantly flows through. •Typically used for trout. •Allow for intensive raising of fish .• constant flow of water.

•Typically raceways are setup in series. •They require 5,000-10,000 gallons of water to raise 1 pound of fish.

Recirculating Systems

•Recirculating systems use tanks and filters to raise fish. •Tanks come in a variety of shapes, sizes, and materials. •Usually several tanks are placed together in a system. •Need 5-10 gallons of water .• Generally discharges 5% of its total system

water per day.

What are the components of a

recirculating system?•There are 3 components to a recirculating system• solids removal• biofilters• dissolved gasses.

Fine & DissolvedSolids Removal

Aeration orOxygenationAir Stone DiffuserPacked ColumnDown-Flow Contactor

Fish CultureTank

Waste Solids RemovalSedimentationScreen FiltersGranular Media Filters

NitrificationRotating Biological ContractorsPacked Bed FiltersExpandable Media Filters

Carbon DioxideRemovalAir Stone DiffuserPacked Column

Solids Removal

•Unused feed and fish waste can cause a problem to recirculating systems. • Rich in ammonia and require lots of oxygen

to be broken down.

•4 types of solids removal systems• Sedimentary tanks• Screens• Sand Filter• Expandable Bed Filter

Sedimentary tanks

•Allow for wastes to settle out of the water to the bottom of the tank. •The tank can then be drained of the solids.

Screens•Water passes through a series of screens. •Particles are trapped in the screen mesh. •Screen mesh gets smaller as it goes down the line. •They can then be removed and cleaned.

Sand Filter

•Water passes through a pocket of sand, gravel, or some other media. •The sand captures particles as water is pumped through it. •Cleaned by backflushing the system. • Water is forced through in the opposite

direction separating the particles from the sand.

Expandable Bed Filter

•Water is pumped through the sand from the bottom. • A coarser media above the sand which

allows for more particles to be trapped.

• To clean this filter, water is forced at a higher pressure through the filter forcing particles through the material and out a drain.

Expandable Bed Filter

•These filters are also good for the removal of ammonia and nitrites. •The coarse material in the filters give good surface areas for bacteria colonization. •These filters are hard to clean and are not as commonly used in small systems.

Biofilters

•Biofilters are necessary to remove ammonia and nitrites. • Tanks where fish are densely stocked,

these levels will get extremely

•4 types of biofilters• Rotating Biological Contractors• Expandable Bed Filter• Fluidized Bead Filter• Packed Tower Filter or Trickle Filter

Rotating Biological Contractors

•These filters rotate in the water allowing for water to cover the filter. •Also helps to

stir and

oxygenate

the water.

Fluidized Bead Filter

•Here beads are constantly turned within the filter. •Tends to have the same effects as the RBC. •Beads allow for a good surface area for bacteria growth. •Movement of the beads also allows for a good exchange of gasses in the water.

Packed Tower Filter or Trickle Filter

•Uses a stack of biofilter material• Allows water to trickle over them.

•Many different designs of these types of filters.

Dissolved Gas Control

•Oxygen, carbon dioxide, and nitrogen need to be exchanged throughout the water in order for the fish to survive. •2 ways to do this• Surface aeration• Diffusion aerators.

Surface Aeration•The surface area of the water is increased. • Nozzles spray water onto the surface of

the water, • Disturbs it allowing water from below to

move up

•Packed tower filters also do a great job for this type of aeration.

Diffusion Aerators

•Put air into the water. • Oxygen contained in air bubbles will diffuse

into the water through the surface of the bubbles.

• Many small bubbles are better than a few large bubbles

•Diffusion aerators also move water in the tank from the bottom to the surface.