Tilapia Production In Biofloc Systems Yoram Avnimelech Tecnion Israel Inst 686i15

TILAPIA PRODUCTION IN BIOFLOC SYSTEMS YORAM AVNIMELECH TECNION, ISRAEL INST. Of TECHNOLOGY

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Biofloc technology is based upon a few principles:  (a) Zero or minimal water exchange,  (b) subsequent development of dense microbial population  (c) managing the microbial population as a part of the pond ecosystem  » (d) adjustment of the C/N ratio to 15 in order to control inorganic  nitrogen concentration in the water. »  The bacteria, forming bioflocs, assimilate TAN, produce microbial  proteins that is consumed by the fish, thus recycle the unused  feed protein. (For more details: Yoram Avnimelech, Biofloc  Technology, A Practical Handbook, World Aquaculture Soc. 2012).

Tilapia, an ideal fish for Biofloc Technology

Grow well in dense cultures Resistant • FILTER FEEDER • Very few studies as • compared with shrimp

Fish Biomass

Normally, 20-30 kg/m2 !times higher than shrimp BFT ponds 10

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High Biomass 20-30 kg/m3 (Up to more than 40kg/m3 (w/o O2) High feeding (ca 500 g feed/m3 per day) Very high microbial activity High floc volume (20-50 ml/l). Very high natural feed storage. High levels of feed residues Need to drain out daily (or twice daily) excessive sludge. Pond constructed to facilitate sludge draining and perfect mixing. High and effective aeration: 10-20 hp/1000 m2 pond

:Implications

Drain bottom sludge twice daily till you get clear water

» Bio flocs are made of bacteria, protozoa, feed  residues etc. » Bioflocs size may reach A few mm diameter » Effectively harvested by tilapia

200 µm

200 µm

x10

x10

x20

200 µm

x10

Bio flocs are made of bacteria, protozoa, etc. Typicaly their diameter is 0.1-2 mm.

» Normally, fish or shrimp recover just ~25% of  feed protein. » In bacterial controlled ponds, they eat the  protein twice; Once in the feed and then they  consume microbial protein. The protein  recovery reaches almost 50%.

» Protein is the most expensive part of the feed. 

Protein Recycling

BFT

control

Expt. # 1 days 51

16.6

11.1

FEED C/N

2.0b

1.59a

2.17

2.62

2.42

4.38

0.583

0.848

)%(Daily Gain FCR PCR FEED COST )US$/Kg fish( Exp. # 2

16.6

11.1

2.22b

1.63a

2.02

2.62

2.18

4.35

0.543

0.848

)30 days(

C/N )%(Daily gain FCR PCR Feed cost (US$/Kg fish)

Results 1: % 15N in fish

» Bioflocs were taken up by fish and degraded  biologically. Yet, the amount of bioflocs stayed  almost constant. This implies that new flocs are  constantly produced (using the excreted N). » The residence time of bioflocs was calculated to  be around 8 hours. The flocs seem to be a very  dynamic system. » most cells in the flocs are young and active.

Residence time of bioflocs

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Conventional fish, shrimp ponds 20-25% BFT Tilapia ponds (Avnimelech) 45% BFT Shrimp ponds (McIntosh) 45% Closed shrimp tanks (Velasco) 63%

» BFT shrimp ponds, 15N study 18-29% of total N consumption (Michele Burford et al.) * Tilapia, 15N Study, flocs supplied about 50% of fish protein requirement. (Avnimelech).

Data on feed protein utilization

» Fish or shrimp growing in BFT systems eat the pellets when applied, but eat bioflocs all the time. » Confirmed in a work done by Albert Tacon with shrimp. » Observations with tilapia. » Effects on lowering of FCR in tilapia production

Feed Utilization

SPECIAL USES, ADDED VALUES

DESERT AQUACULTURE

Effects on propagation Shrimp broodstock grown in BFT  have earlier sexual maturity And higher productivity Similar result with tilapia Work by Julie Ekasari ?Better nutrition?  Fatty acids ? Hormonal effects

Summary of fatty acids analysis on the collected bioflocs Fatty acids

Total Fatty Acids%

Total n-3

1.33

Total n-6

19.70

Total n-9

12.97

LA

13.43

ALA

0.36

EPA

0.56

DHA

0.32

AA

1.30

n-6 fatty acids is  n-6 fatty acids is  essential for tilapia  essential for tilapia  and its reproduction  and its reproduction  (Watanabe 1982) (Watanabe 1982)

Protein : 37 – 46% DW Lipid : 11.9 % DW

Biofloc considerably high in AA (Arachidonic Acid) •• Biofloc considerably high in AA (Arachidonic Acid) AA is beneficial for fertilization rates  stimulates testicular  •• AA is beneficial for fertilization rates  stimulates testicular  testosterone in goldfish (Izquierdo et al 2001) testosterone in goldfish (Izquierdo et al 2001)

What triggers the fish to spawn? (Rocha 2008) Physiological factors. 2 Hormones ˃ Morphological changes ˃ Mobilization of energy reserves ˃

Blood total cholesterol in fish in BFT tanks was higher • Cholesterol  precursor of steroids hormones Blood glucose as an indicator of mobilization of energy  • reserves Fish growth •

Results: Blood total cholesterol

Higher concentration in  •• Higher concentration in  BFT  higher  BFT  higher  concentration of  concentration of  hormones were  hormones were  involved ??involved

Results: Blood glucose Higher concentration in  •• Higher concentration in  BFT  BFT  More energy was  •• More energy was  mobilized for  mobilized for  reproductive  reproductive  activities activities More energy supply •• ??More energy supply

Results: Average body weight Despite of more active reproductive  Despite of more active reproductive  performance the female in BFT tanks  performance the female in BFT tanks  grew better grew better

Yet, the fish in BFT required  Yet, the fish in BFT required  less feed less feed vs 8.3 kg/tank 9.3 9.3)) ((vs 8.3 kg/tank

Results : Total fish fry production

a

Julie Eskari

b

» Tilapia fingerlings (120 g) stocked to overwintering facility on January 4, 2011. » Feeding ~ 1% BW » On February 18, they weighed  171 g » Daily growth of 1.16 g/fish » FCR = 0.5 

:Fresh results from the field

OVER-WINTERING

EFFECT OF WATER EXCHANGE RATE ON PRIMARY AND SECONDARY INFECTION OF FISH BY STREPTOCOCCUS Treatment Total infected Sick fish Dead fish

Control

a)Injected fish a)Noninjected fish

BFT

11 16

11 Control ( 4.7 ) BFT

3 ( 1.4 )

( 2) (2)

( 1.5 )

2 (9) 4

4

( 1.0 ) 1.3

9 Control 12 (3)

(5)

BFT

7

High exchange

1.8 ( 1.7 )

ASP

 High water exchange = 0.5l/min per kg fish (700% per day)  BFT< Limited water exchange = 10% per day

Luo and coworkers in China reported Yields of 45kg/m3. Higher production and lower FCR as compared with RAS. Higher concentrations of Superoxide Permutase .

»Conclusions » Biofloc technology is especially adapted to raise tilapia production up to 20-30 kg/m2. » This can be done using not too expensive system. » BFT enables feed recycling, high feed quality and reduced expenses. » BFT reduces disease. » The system is friendly and forgiving. » More research is needed

» Cultivo de tilapia en sistemas biofloc es simple, fácil y rentable. • Tilapia como filtrador es feliz en esos sistemas. • Se ahorra los gastos de alimentación (~ 30%) y comer mejor. • Menos enfermedades. • Mayor crecimiento y menor FCR. • La manera más rápida de iniciar la producción intensiva de tilapia. • Si necesita ayuda, estaré feliz de hacerlo: » [email protected]