Biofloc technology (BFT) is a system of

aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. Nelu ...

that uses "microbial biotechnology to increase the efficacy and utilization of fish feeds, where toxic materials such as nitrogen components are treated and converted to a useful product, like a protein for using as supplementary feeds to the fish and crustaceans." In high nitrogen environments, the beneficial

heterotrophic A heterotroph (; ) is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter. In the food chain, heterotrophs are primary, secondary and tertiary consumers, but ...

bacteria are typically limited by carbon levels. Therefore, adding a readily available source of carbon allows the bacteria to simultaneously take up a greater portion of nitrogen (contributing to better water quality) as well as generate biomass that then serves as food for the cultured animals. The species of

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

and

crustaceans Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of Arthropod, arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquat ...

must be carefully chosen in order for the BFT system to realize its full potential.

History

The first BFT was developed in the 1970s at Ifremer-COP (French Research Institute for Exploitation of the Sea, Oceanic Center of Pacific) with ''

Penaeus monodon ''Penaeus monodon'', commonly known as the giant tiger prawn, Asian tiger shrimp, black tiger shrimp, and other names, is a marine crustacean that is widely reared for food. Taxonomy ''Penaeus monodon'' was species description, first described ...

'', ''Fenneropenaeus merguiensis'', '' Litopenaeus vannamei,'' and ''L. stylirostris''. Israel and USA (Waddell Mariculture Center) also started Research and Development with Tilapia and ''L. vannamei'' in the late 1980s and 1990s. Commercial application started in 1988 at a farm in

Tahiti Tahiti (; Tahitian language, Tahitian , ; ) is the largest island of the Windward Islands (Society Islands), Windward group of the Society Islands in French Polynesia, an overseas collectivity of France. It is located in the central part of t ...

(

French Polynesia French Polynesia ( ; ; ) is an overseas collectivity of France and its sole #Governance, overseas country. It comprises 121 geographically dispersed islands and atolls stretching over more than in the Pacific Ocean, South Pacific Ocean. The t ...

) using 1000m² concrete tanks with limited water exchange achieving a record of 20–25 tons/ha/year in 2 crops. A farm located in

Belize Belize is a country on the north-eastern coast of Central America. It is bordered by Mexico to the north, the Caribbean Sea to the east, and Guatemala to the west and south. It also shares a maritime boundary with Honduras to the southeast. P ...

, Central America also produced around 11-26 tons/ha/cycle using 1.6 ha poly-lined ponds. Another farm located in Maryland, USA also produced 45-ton shrimp per year using ~570 m³ indoor greenhouse BFT race-ways. BFT has been successfully practiced in large-scale shrimp and finfish farms in Asia, Latin, and Central America, the USA, South Korea, Brazil, Italy, China, India, and others. However, research on BFT by Universities and Research Centers are refining BFT for farm application in grow-out culture, feeding technology, reproduction, microbiology, biotechnology, and economics.

The role of microorganisms

Microorganisms A microorganism, or microbe, is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells. The possible existence of unseen microbial life was suspected from antiquity, with an early attestation in ...

play a vital role in feeding and maintaining the overall health of cultured animals. The flocs of bacteria (biofloc) are a nutrient-rich source of proteins and lipids, providing food for the fish throughout the day. The water column shows a complex interaction between living microbes, planktons, organic matter, substrates, and grazers, such as

rotifer The rotifers (, from Latin 'wheel' and 'bearing'), sometimes called wheel animals or wheel animalcules, make up a phylum (Rotifera ) of microscopic and near-microscopic Coelom#Pseudocoelomates, pseudocoelomate animals. They were first describ ...

ciliate The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to flagellum, eukaryotic flagella, but are in general shorter and present in much larger numbers, with a ...

protozoa Protozoa (: protozoan or protozoon; alternative plural: protozoans) are a polyphyletic group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic debris. Historically ...

and

copepod Copepods (; meaning 'oar-feet') are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (living in the water column), some are benthos, benthic (living on the sedimen ...

s which serves as a secondary source of food. The combination of these particulate matters keeps the recycling of nutrients and maintains the water quality. The consumption of floc by cultured organisms has proven to increase the immunity and growth rate, decrease feed conversion ratio, and reduce the overall cost of production. The growth promotional factors have been attributed to both bacteria and plankton, where up to 30% of the total food is compensated in shrimp.

Species compatibility

In BFT, there is a species compatibility norm for culturing. To improve growth performance, the candidate species must be resistant to high stocking density;

Population density Population density (in agriculture: Standing stock (disambiguation), standing stock or plant density) is a measurement of population per unit land area. It is mostly applied to humans, but sometimes to other living organisms too. It is a key geog ...

, adjust to fluctuations in dissolved oxygen (3–6 mg/L), settling solids (10–15 mL/L) and total ammonia compounds, and have omnivorous habits or the ability to consume microbial protein.

References

{{reflist Aquaculture