Article by Scott Day
In agriculture, and all aspects of society today, we are striving towards intuitive ideas which can be used to increase efficiency, decrease waste and still
ensure a wallet full of buffaloes.
A
quaculture is no different, and with an average
annual growth rate of
close to 9% over the last
3 decades, it has risen to supply
more than 50% of seafood eaten
worldwide. With the collapse of
around 85% of the world’s wild fish
stocks and driven by this desperation for a solution, we have seen
aquaculture at the forefront of innovation and technology.
Through its development, aquaculture has had its fair share of time in
the limelight, with concerns raised
around the environmental degradation it has caused as well as the use
of more fishmeal to produce a kg of
fish. But with the industry being
driven by innovation and technology, many of these old fashioned
problems have been solved and today we can produce species such as
Tilapia and Carp (the 2 largest aquaculture fish species produced)
without a trace of fishmeal.
From this ethos rooted in innovation, and taking into account current global challenges such as food
security, water security and the environmental impact of development, the concept of Biofloc Technology was born.
It deviates from the conventional
ways of thinking, and starts off by a
plastic lined pond or tank being
filled with water a month or so before you plan to introduce fish. This
would generally be done early on
after the winter, so that you can
maximize your warmer growing
season when using species such as
The recycling of nutrients in a Biofloc system
Tilapia. The size of the water body
varies from ponds of more than a
hectare to round tanks 2m in diameter. The water is then fertilized
throughout the month with a
source of Nitrogen as well as a Carbon source. This can be done with a
normal NPK nitrogen fertilizer or an
organic fertilizer, and you can add
the carbon through any carbohydrate source such as maize meal,
flour, molasses etc. You want to
add 0.5-2.5mgN/l which equates to
about 5-25kg/ha pond of 1m deep.
This is done to fuel the microbial
growth in the system, and start producing the flocs which are clumped
together collections of microorganisms up to 2mm in diameter and
are suspended in the water. In order to keep the flocs in suspension
and to provide for the oxygen
Imhoff cones with varying levels of
biofloc