Aqfs-601 Lecture no#2 04-03-11
Advantages & Disadvantages of the Aquaculture
Helps insure a supply of desired aquacrops (wild supplies may be very
limited aquafarming helps insure availability).
Can control environments of production (feeding fish nutritional ,wholesome
feeds eliminates possibility of contamination with harmful substances ,such
Helps provide nutrients essential in human diet.
o Technology not available for many possible crops.
o Lack of knowledge about aquaculture.
o Competition from wild fish & sea food.
Types of Aquaculture Production Systems:
Level of Intensity :
Intensity refers to diversity (crowding together) of the
aquacrop being produced.It may be Extensive , Intensive & Intermediate.
Extensive systems involve low population density, minimal control over the sytem
,little intervention by the farmer,e.g. small natural or artificial ponds or lakes.
Intensive systems involve producing aquacrops at a high rate of
stocking.Considerable skill management & financial investment is needed .Tanks
and Raceways are commonly used with continuously flowing water.The potential for
returns is greater than extensive systems .
Intermediate systems involve some principles of both extensive and intensive
systems.In this artificial ponds are used ,fish are stocked at a rate requiring feed &
water aeration but not in flowing water .Most catfish farming uses intermediate
Kind of Water Facility :
It refers to design of the water enclosure & water
Water enclosures include ponds,cages,raceways & tanks.In pond culture, aquacrop
is placed in the pond without restriction by cages & pens .Cages are used to confine
fish to a certain area of the water .Raceways are long narrow structures that use
flowing water.Tanks may be round or rectangular & use flowing water.
Water movement refers to whether or not water in enclosure flows.The density at
which fish can be stocked depends on the rate of water flow.
Type of System :
Classified on the basis of the use and re-use of water.They may
range from closed to open.
An open system is one in which water is pumped in at one place & removed at
another .The water is used once and discarded .This involve running water into a
holding pond or into a river.Enviornmental regulations may not allow certain water to
be run directly into streams .
Water may be re-used by flowing from one tank to other to another in series .Water
is not filtered to remove uneaten suspended feed .
Recirculation involves pumping the water back through the same water facility.The
water is often re-conditioned, it may involve filtering , aerating procedures to keep
water of high quality.
A closed system is one in which no new water is added ,involves filtering and
recycling of water, and it must be treated to remove uneaten feed , fish excrements.
Water Temperature :
Different crops require varying temperatures.It may be
cold , cool ,or warm.It is important for potential aquafarmer to select an aquacrop
suitable to environment.
Kind of Species :
Monoculture is a production system in which only 1 species is
grown at a time.
Polyculture involves growing two or more species together.The species need to be
compatible in behavior & environmental requirements,in a good polyculture ,species
do not prey on each other , also do not directly compete with each other for food.