Biofloc Technology in
“Science is not changing everyday, but our
understanding is changing- Magada”
Most of the efforts in research is to understand the nature and the truth.
Even in the field of aquaculture many such efforts led to blue revolution in
the world. The global fish production is 158 million tonnes (mt) of which 66 mt
come from freshwater. India is producing 10.07 mt of fish and 6.0 mt is
contributed from freshwater aquaculture. India is earning 47000 crores by
exporting 12.5 lakh tonnes of fish and fishery products. Of which 20,000+ crores
contributed by export of Litopenaeus
Vannamei -the white shrimp. After a major disease outbreak in tiger shrimp
farming, many farmers started culturing the white shrimp which is native to
Latin America.
Why Biofloc
Technology (BFT)?
Biofloc
technology is a technique of flocculating heterotrophic food in
aquaculture ponds through balancing carbon and nitrogen in the system. Biofloc
is a consortium of algae, bacteria (Both useful and pathogenic), saprophytes
and such other microscopic plankton. About 60% of the microscopic natural food
in the pond is less than 60 micron which even fishes cannot feed on them. When
they are flocculated, they are available for fishes and it forms a very
nutritive food with 12-25% protein, 15-32% dry matter and 30-60% carbohydrates
on dry weigh matter. This flocculation enhances water quality and reduces the
requirement of supplementary diet. BFT is all about managing C:N ratio (Carbon
and Nitrogen ratio) and ammonia. If this ratio is maintained more than 10 in aquaculture
ponds, the productivity increases significantly. In other words, it is
recycling of nutrients and nutrients recovery in the form of biomass. The
nitrogen is available in plenty in any aquafarm. It comes from feed waste,
faecal matter and dead and decayed material in the pond but carbon is a
limiting factor. Hence, it has to be supplied from the outside. In many
countries, farmers use molasses. These days’ molasses is in high demand and it
goes for alcohol production. As alternatives joggery or sugar can be used.
Agent of
Change...
Mr Sunny D’Souja, who
has worked in different fields of aquaculture, started practicing this BFT in
his farm. He has 16000 m2 (4 acres) of land at Haleyangadi-20 km
away from Mangalore, Karnataka, India. He has constructed 10 ponds of different
sizes with a water spread area of 13000 m2 and they lined with 160
gsm, 250-400 micron, UV treated plastics. The average depth of pond is 1.5 m. He
uses the water from nearby creek where the salinity ranges from 8-35 ppt in a
year. It is a recycling system, where there is no water exchange unless there
is a heavy algal bloom and high evaporation. He uses 25 HP capacity air blowers
24X7 and air is passed through special air stones of 1.5 m and 4 inch diameter
which has the capacity of dispersing the air bubbles as small as 0.3 mm. Air
stones are positioned at the bottom as
many 100/acre. (See the farm with this link https://www.facebook.com/manu.tvm/videos/469886750070736/)
He stocks the ponds with L. Vannamei PL @ 250/m2 and
used commercial feeds with high protein. With support of check trays, feeding
is ad libitum. After 60 days, stock is thinned out by culling the larger ones.
Later every 15 days or depending on the demand and price, stock is marketed. In
last crop, in about 110 day of culture period, he has harvested 17 t/acre and
sold for Rs. 310/kg of shrimp with 50 count. He cost of production is about Rs.
130-150/kg. The gross revenue was Rs. 55 lakhs in 3.25 acres and earned net
profit of 35 lakhs.
Success breeds
success
The average L.
vannamei production in India is about 8-10 t/ha, but Mr Sunny D’ Souja has
harvested 35-40 t/ha. The greatest point to be noted by reading this report is
Mr Sunny D’Souja, despite possibility of increasing competitors in his
vicinity, he reveals all the business secrets and he wants many more people to
take up this business. Since the demand for shrimp is huge, many more can
harness the opportunity along Karnataka coast. ICAR-Krishi Vigyan Kendra,
Dakshina Kannada will play a facilitative role in up-scaling this project along
the Karnataka coast.
Fig
2. Check Tray has become harvesting tray
Fig 2. Ponds with lining and aeration
Save Power
This BFT requires continuous power supply to
support the aeration. In exigency, without aeration, the systems can be managed
for 3-4 h but not beyond that. Normally, to produce 400-500 kg of biomass, it
requires 1 HP, but in BFT system it is possible to produce 1000-1150 kg/HP.
This reduces the cost of production (CoP) drastically. In spite of regular
power supply, there must be backup diesel operated generator of required
capacity. Since BFT saves energy over 50%, this is most often referred as
“Ecofriendly”
Environment
friendly
Apart from saving power, the BFT is truly
environmental friendly system. The major issue in shrimp farming is secondary salinization
of agriculture and other adjacent lands. This is common issue due to seepage
and percolation. Since BFT is recycling system, there is least water exchange.
HDPE pond lining completely avoids the seepage and percolation. The organic
load of the ponds are efficiently recycled, there is no issue of contaminating
the nearby water sources.
You love
Economics
The average vannamei shrimp production is about
8-10 t/ha. With BFT, the potential production goes over 40 t/ha. The cost of
production ranges between Rs. 130-160/kg. The average gate value of vannamei
with a 40 count/kg is Rs. 300+/kg. Net profit over 100% in 110-120 days is like
growing gold in the water. Comfortably, one can take two crops per year.
Because of the scale of economy, profits are high. Though we have least control
over market price, with better management the CoP can be reduced and profit
margin can be increased.
The overall
advantages of BFT are
§
No water exchange, only recycling
§
Stocking density can be increased
§
High productivity
§
Less power consumption
§
Sustainable
§
Environmental friendly
§
Better FCR
§
Low disease incidence
§
Uniform growth
§
High income
Disadvantages:
§
High energy input
§
Power failure is critical. Backup
power supply is must
§
UV treated HDPE lining is required
§
Non availability of skilled manpower
to operate BFT
Disclaimer:
This article is a document of personal field experience of
the author. Karnataka Veterinary, Animal and Fisheries University, Bidar or any
other institutions in India and abroad are not responsible for the content,
data or opinions in this article. Farmers and entrepreneurs need to take
author’s and other experts’ opinion before implementing it in the field.
