The biofloc is a protein-rich aggregate of organic material and microorganisms that forms in aquaculture systems. Biofloc technology maintains water quality and provides nutrients by balancing carbon and nitrogen through the addition of carbon sources like molasses. It has been successfully used in tilapia and shrimp farming and allows for high stocking densities through natural water treatment. Key factors that must be controlled include carbon to nitrogen ratio, dissolved oxygen, pH, and ammonia, nitrite and nitrate levels.

2. The biofloc is a protein rich macro-aggregate of organic material and
micro-organisms including diatoms, bacteria, protozoa, algae, fecal
pellets, remains of dead organisms and other invertebrates.
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3.  Works on the basic principle of flocculation within the system (Avnimelech 2009).
 Biofloc technology has been successfully implemented in aquaculture specially tilapia
and shrimp farming.
 Biofloc technology is a technique of improving water quality in intensive aquaculture
through balancing carbon and nitrogen in the system.
 The basic requirement for biofloc system operation include high stocking density, high
aeration and lined ponds.
 It has basically two major roles i.e. water quality maintenance and providing nutrients
(Emerenciano et al., 2013).
 A crucial factor in this system is the control of biofloc in tanks/ ponds during operation.
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4. CARBON TO NITROGEN RATIO
 C:N = 15 : 1
(Emerenciano et al., 2017)
› C: N = 20:1
(Intech, 2017)
EXTERNAL SOURCES OF CARBON
 Rice
 Molasses
 Corn
 Starch
 Sugar
(Intech, 2017)
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5. 5
Carbon-Nitrogen (CN) Ratio with Zero Water
Exchange
The CN Ratio Calculation is based on Fish Feed Protein Percentage
and the below chart shows the CN Ratio of the feed materials
(Avnimelech, 2009).
Protein Percentage (%) CN Ratio
15 21.5
20 16.1
25 12.9
30 10.8
35 9.2
40 8.1
As per the reported literature, the CN Ratio of 10:1 and
15:1 are more successful. It has been reported that CN
Ratio of 10:1 does not require even water exchange.

6. 6

7.  Low investment
 Production of approximately 600 kgs of Bio-mass within 5-6 months
(tilapia culture).
 Suitable for tropical conditions.
 Preferably, tilapia and shrimps are being cultured under biofloc setup.
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8.  Intensive Aquaculture Expansion
 To develop sustainable aquaculture systems
 To support economic and social sustainability
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9.  A basic factor in designing a biofloc system is the species to be cultured.
 Biofloc system is most suitable for species that can tolerate high solids
concentration in water and generally tolerant of poor water quality.
 Species such as tilapia and shrimps have physiological adaptations that
allow them to consume biofloc and digest microbial protein.
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10. System Stocking
density
Aeration
(hp/ha)
Sustainable
feeding rate
(kg/ha/day)
Carrying
capacity
Shrimp pond 125-150PL/
m2
25-35 400-500 20-25t/ha
Tilapia 20-25
fingerlings/
m3
130-150 1750-2000 15-20kg/ m3
(Hargreaves, 2013)
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11.  There are two basic types of biofloc systems i-e. system exposed to natural
light and system not exposed to sunlight.
1. Green water biofloc/ Outdoor system
2. Brown water biofloc/ Indoor system
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12. Green water biofloc:
 Biofloc systems are exposed to natural light include outdoor, lined ponds
or tanks for the culture of shrimp or tilapia under greenhouses.
Brown water biofloc:
 Some biofloc systems (tanks) have been installed inside closed buildings
with no exposure to natural light.
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13.  Dissolved oxygen (Above 4 mg L-1)
 Temperature (28-30 0C for tropical species)
 pH (6.8-8.0)
 Total ammonia nitrogen (Less than 1 mg L-1)
 Nitrite (Less than 1 mg L-1)
 Nitrate (0.5-20 mg L-1)
 Orthophosphate (0.5-20 mg L-1)
 Alkalinity ( Above 100 mg L-1)
(Emerenciano, 2020)
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14.  The flocculation of microbial communities is a complex process.
 Within the floc’s matrix a combination of physical, chemical and
biological phenomena is operating.
 The exact mechanisms and methods to engineer microbiological flocs
remain largely unknown.
 These structures form a matrix that encapsulates the microbial cells and
play a major role in binding the floc components together.
 They are typically made up out of polysaccharides, protein, humic
compounds, nucleic acids and lipids.
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15. 15
Floc measurement using Imhoff cone
Ideal: 5–15 mL L−1 (shrimp),
5–20 mL L−1 (tilapia fingerlings)
and 20–50 mL L −1 (juveniles and adult tilapia)

16.  Biofloc is a rich lipid-protein source which could be utilized by the first
stages of shrimps brood stocks for the gonads formation and ovary
development.
 Furthermore, production of brood stock under biofloc technology could be
located in small areas close to hatchery facilities, preventing spread of
diseases caused by transportation.
 Biofloc technology could enhance spawning performance as compared to
the conventional pond and tank- reared system, respectively i.e. high
number of eggs per spawn and high spawning rate.
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17.  Aquaponics is a sustainable food production system that combines a
traditional aquaculture with hydroponics in a symbiotic environment.
 Nowadays, biofloc technology has been successfully applied in
Aquaponics. The presence of rich biota (microorganisms of biofloc) and
a variety of nutrients such as micro and macro-nutrients originated from
un-eaten or non-digested feed seemed to contribute in plant nutrition.
 However, high concentration of solids may cause excessive adhesion of
microorganism on plant roots (biofilm) causing its damage, lowering
oxygenation and poor growth.
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18. Advantages:
1. Zero water exchange- less than 100% exchange for whole culture period.
2. Production (carrying capacity) 5-10% above than traditional system.
3. FCR low between 1.0 to 1.3.
4. Production cost lowered by around 15-20%.
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19. Disadvantages:
1. High energy input
2. Power failure critically maximum upto one hour at any time (better
zero hour failure)
3. Technology similar but more advance therefore, requires trained
technicians.
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20.  Avnimelech, Y., 2009. Biofloc Technology- A practical guide book. The World
Aquaculture Society. Baton Rouge, Louisiana, United States. 182pp.
 M. Emerenciano, G. Cuzon, M. Arevalo, M.M. Miquelajauregui, G. Gaxiola. Effect of
short term fresh food supplementation on reproductive performance, biochemical
composition, and fatty acid profile of Litopenaeus vannamei (Boone ) reared under
biofloc conditions. Aquaculture International, 21 (2013), pp. 98-1007.
 M.G.C. Emerenciano, L.R. Martinez-Baeza . Biofloc technology: A tool for water
quality management in aquaculture. Intech (2017).
 D. G. Emerson, G. Mauricio, E. Coelho. Biofloc technology adjusting the levels of
digestible proteins and digestible energy in diets of Nile tilapia juveniles raised in
brackish water. Aquaculture and Fisheries (2020).
 John A. Hargreaves. Biofloc production system for Aquculture. Southern Regional
Aquaculture Center (2013).
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