Frequently Asked Questions Related to Biofloc Based Fish Farming

Posted by Dr. H Saha on

Biofloc Based Fish Farming

Who is the Founder of Biofloc Based Fish Farming?

Professor Yoram Avnimelech from Israel is one of the founders of Biofloc technology. He is the author, among others, of the book entitled “Biofloc Technology – A Practical Guide Book,” which was translated into Vietnamese. He is working as Professor Ameritus in the Faculty of Civil and Environmental Engineering, Israel Institute of Technology. He has worked for a few years on the development of the Biofloc Technology (BFT), and wrote a manual on this system (3 editions, almost all sold out).  He gave a number of courses on biofloc Technology in many countries including India, Mexico, Brazil, Thailand, Indonesia, Korea, China, Belgium, Colombia and more. Presently, due to the corona virus and stoppage of travel, He is consulting and guide for biofloc technology using electronic media. He has also developed new aeration systems which are energy efficient and help sludge control.

What is the Biofloc fish farming?

Biofloc based fish farming commonly called as Biofloc fish farming is a technique of rearing and growing fish using biofloc technology. Through biofloc technology, water quality in the aquaculture system is maintained by balancing carbon and nitrogen in the system. Under this technology, C/N ratio are maintained to convert inorganic nitrogen into organic nitrogen i.e., protein in the form of microbial biomass that can be consumed by fish. Thus, the technology is a sustainable method to control water quality, with the added advantage of producing proteinaceous food in in-situ condition. 

Is Biofloc fish farming successful?

Biofloc is a Profitable Method of Fish Farming. Rearing of fish at high-density requires some waste management system, and biofloc technology provides the same. Biofloc system is profitable in mainly three ways. Firstly it manages the waste water most efficiently as well as quickly as compared to many other methods and thus providing environmental benefits. Secondly, the waste is being recycled and utilized for fish production which in return gives monetary benefits. Hence, it is a sustainable and eco-friendly process. Thirdly, with the help of biofloc technology fishes can be grown at higher stocking density and thus helps in increasing the vertical production. 

How we can use the waste from Biofloc based fish farming?

During the biofloc based fish farming waste in the form of sludges are produced which need to be drained out periodically. The waste from the system contains high organic load as well as nutrients. The sludges can be used for various purposes like composting, manuring crops, and others. Recently, attempts were taken to use the sludges to culture tubifex worms in artificial system and results are encouraging. As tubifex worms are used as fish food and it has very premium price in the markets.

Which fish is suitable for Biofloc?

Almost all the cultivable species can be grown in biofloc based farming system, however, some exception are always there. Some species are having physiological adaptation which allows them to consume and digest biofloc/microbial protein more efficiently as compared to other species. Shrimp and tilapia are considered as most efficient fishes for Biofloc based farming system. In India, shrimp, tilapia, pungus, carps, magur, koi (Anabus spp.), singhi, pabda etc. are being grown in biofloc systems.

Is Biofloc fish healthy?

The flocs themselves are protein-rich and provide fish and shrimp with a good source of vitamins and phosphorous. Many researchers have shown that allowing the microbial flocs to proliferate in a system can improve water quality and immobilize toxic inorganic ammonia or ammonium to organic nitrogen i.e., protein. No such report has been seen in the recent past about any negative effect of biofloc fish on human health. More studies need to be undertaken to elucidate  any negative effect on consuming fish grown using biofloc based farming system.

Which bacteria are used in Biofloc?

Biofloc are not only consisting of bacteria. It is a complex of different types of microorganisms. Those conglomerates of microorganisms remain in the symbiotic relationship and helps in maintaining the water quality. Conglomerates of microorganism are consisting of heterotrophic bacteria, algae (dinoflagellates and diatoms), fungi, ciliates, flagellates, rotifers, nematodes, metazoans and detritus.

Which commercially available probiotic are used for biofloc development?

Probiotics containing the conglomerates of different heterotrophic bacteria are used for biofloc development. Mainly Bacillus spp. group of bacteria are useful for the purpose. Most popular bacteria species used in the commercially available probiotics are:

  • Bacillus subtilis
  • Bacillus megaterium
  • Bacillus licheniformis
  • Bacillus polymyxa

Which one is better, Recirculatory Aquaculture System (RAS) or Biofloc?

Studies have shown that individual shrimp weights, total biomass, and FCR were all significantly better in the clean water systems as compared to the biofloc system. Studies have suggested that Recirculatory Aquaculture System is more productive as compared to the biofloc system. Apparently, RAS is better than Biofloc system. However, profitability in terms of investment involved in both the cases need to be evaluated based on the demand and supply requirement of the produce from the system. RAS installation cost is many times higher than the biofloc and that’s the reason why biofloc based culture system is more popular among the farmers as compared to the RAS in India

How much fish can be produced from a Biofloc tank?

In most of the on-field condition it has been found that the biofloc tank can accommodate 25 kg of fish per 1000 litre of water. However, it totally depends on the management of the water quality parameter on regular basis. Many farmers claimed to produce 250kg of fish from 10000 litre of biofloc tanks within 6 months of culture period. Number of fishes that can be reared in biofloc tank also varies with the species for culture as well as their sizes.

How many fish can you stock in a 1000 Litre tank?

As per the general production report, 25kg of fish can be harvested from 1000 litre of tanks. Thus, before stocking fishes in the biofloc tank, one should be aware about the target fish size that they want to harvest from the tank.

Suppose the target size for harvest of fish from the tank is 100 gram.

Then, total number of fish that can be harvested from 1000 litre tank will be 25kg/100 g


=250 numbers.

As mortalities of fish during the culture cycle is a normal consideration, in biofloc system fish mortality can be around 20% in normal condition (assumption). Thus, taking the mortality in to consideration, farmer should stock extra 20% fish in the tank, i.e., 250+20% of 250


=300 nos in 1000 litre tank.

Hence, using this calculation one can estimate how many fishes that can be stocked in a biofloc tanks for fish culture.

What is the most profitable fish to farm using biofloc technology?

Choosing the right fish based on the location, demand and market rate is very important. Almost all kind of fish can be grown in the biofloc based system. However, proper management strategies need to be developed for different species. On the other hand, in terms of profitability only those species should be selected whose market rate is always high and standard protocol for growing that particular species under biofloc system is available. 

What are the Fishes that can be cultured under Biofloc system?

Almost all fish, however only few species have been tried like Shrimp, Tilapia, Salmon, Scallops, Carp fish, etc. 

Is Tilapia farming profitable under Biofloc system?

Tilapia is one of the best species that grow very well under biofloc based farming system.  However, it does not fetch good market price. Due to which sometimes tilapia is not recommended for biofloc system as it does not give sustainable return/profit to the farmer.

However, tilapia can grow rapidly as compared to other fish under biofloc system.

How much does it cost to start a fish farm?

Cost of setting up a biofloc based fish farm depends on many factors which are as follows:

  1. Number of tanks will be installed: More the number of tanks installed less will be the installation cost per tank. However, total cost of the setup will increase with the increase in number of tanks.
  2. Volume of tanks: Volume of tank also influence the maintenance cost of running a biofloc based fish farming. Apart from different input cost, testing different water parameters on daily basis for maintaining proper biofloc system incur costs. For example, if Team A is managing 10 numbers of biofloc tanks of capacity 1000 litre each and on the other hand if Team B is managing one tank of 10000 litre. Then Team B can measure the water quality parameters by testing it once; however, Team A need to repeat the test for all 10 tanks separately on daiy basis and this incur extra cost. Thus, Team B can spend less time and money in testing water paramemter of 10000 litre volume as compared to Team A.
  3. Location of the Firm: Based on the location the installation cost of a Biofloc unit varies significantly.
  4. Provision of power supply: The major limitation of biofloc based fish farming is the availability of 24x7 power supply. And in villages 24x7 power supply becomes a challenge sometimes. Thus, in order to get 24x7 power supply, a farmer needs to keep the provision of alternative power supply using Inverter or generator. And the cost of installation of emergency power supply incurs heavy cost and sometimes the cost remains more than the cost of the biofloc tanks itself.

How much can you make in one tank through biofloc fish farming?

It totally depends on the selling price of produced fishes. If the rates are high then the profits will also be high. As the production cost almost remains constant whereas the selling prices of the fishes vary widely with season, location, species, sizes of fishes etc. however, to have an decent profit from a biofloc based farming system, the selling price of the fishes should be more than rupees 250/- atleast.

How do you control ammonia in a Biofloc tank?

Controlling ammonia is the main principle of the whole biofloc technology. There are many strategies to control ammonia in the biofloc tanks. However, maintaining the C:N ratio by adding carbon sources in the tank is the main strategy to control ammonia. Ammonia can also be controlled by adding FCO in the tank. The fundamentals of adding carbon in the tank for maintaining the ammonia in the biofloc tank can be learned from the video given below.

The calculator for calculating the amount of molasses (carbon source) that are needed to be added in the tank is given below.

What is Biofloc calculator?

It is a calculator used for estimating the amount of carbon source (in the form of molasses) needs to add in the tank to achieve desired Carbon to Nitrogen ratio. In the biofloc calculator only by providing some basic information the requirement of carbon sources can be calculated. The link for the Biofloc calculator is given below for the needful. The calculator of the Biofloc was developed by Dr. Himadri Saha.

Biofloc calculator is of two types:

  1. Calculator for maturation phase- During the maturation phase one need to input only the amount of feed being added as well as the crude protein content of the feed. During the maturation phase high C:N ratio is required to stabilize the heterotrophic community of the bacteria. Generally the required C:N ration varies between 12-20:1 for the maturation phase. From the link given below, the biofloc calculator can be access freely and the calculation can be done easily by inputting the required information (
  2. Calculator for maintenance phase- After achieving the maturation phase the biofloc level need to be maintained. However, for maintaining the desired floc level lower C:N ratio is required as compared to maturation phase. Generally, the recommended C:N ratio for maintenance phase is 6:1. For calculating the amount of carbon source in the form of molasses in the biofloc calculator one need to input the Total Ammnoia Nitrogen (TAN) of the water and the volume of water in the tank. The link of the biofloc calculator as well as the link of the video on how to use the calculator is also given below.

Biofloc calculator by Dr. H. Saha

How to reduce ammonia in emergency in a Biofloc tank?

Ammonia reduction in biofloc tanks by adding carbon sources or FCO need certain time. However, sometimes circumstances arises where one need to reduce the ammonia buildup immediately. In that case Zeolime can be added.

What is FCO?

FCO means Fermented Carbon Organic. In this technique carbon source are being fermented with the help of heterotrophic bacteria in presence of other nutrients.

How to Prepare FCO?

Add the following in 20 litre water in a separate container

  • 50 gm of Probiotic powder
  • 600 gm Molasses
  • 600 gm Raw Salt (iodine free)

For fast activation of bacteria keep the container air tight. However, slight aeration need to be provided to keep on mixing the ingredients as well as to avoid purification of the ingredients. The FCO takes 7-8 days to get activated and it's color become orange.

How FCO are added in the Biofloc tanks?

Activated FCO can be added into the biofloc tank on regular basis based on the requirement. Addition of FCO provide readily utilizable carbon source with heterotrophic active bacteria into the biofloc tanks which is required for maintaining the ammonia as well as biofloc level.

Why addition of FCO is necessary for better Biofloc Production?

  • It provides fresh heterotrophic bacteria to the system
  • It replaces the old and contaminated bacteria from the system
  • It provide carbon sources for the bacteria in readily utilizable form
  • It promote the growth of biofloc
  • It reduces the requirement of probiotic

Why Biofloc Setup fails?

Biofloc based fish farming requires highly technical guidance. Most of the amateur biofloc fish farmers are starting the project without proper knowledge and guidance. In country like India many are claiming themselves to be an expert of biofloc fish farming without having the basic degree on Fisheries and Aquaculture. At least a Bachelor of Fisheries Science (BFSc) graduates can be a technical expert for supporting one's biofloc setup. Anyone interested to start a Biofloc setup can contact us for technical supports. We have qualified experts, faculties as well as scientist to guide you in running biofloc farm successfully. Multinational Aqua Research Centre provides all kind of technical supports to start fisheries activities starting from fish breeding, seed rearing to growing out table size fish. We provide all  kind of technical supports related to fisheries and aquaculture and our experts are from India as well as from various other parts of the globe. Please feel free to contact us for technical and product support.

Multinational Aqua Research Centre
Abhoynagar, Agartala, Tripura (W)-799005, India
Mob: 07005820412

Where we can get Biofloc Training? 

 To learn Biofloc based farming system one need to devote time for more than 6 months at least. Any training for 1-2 days does not help the farmers to learn the system completely and any incomplete learning is very dangerous. may be these type of 1-2 days training are the main reason for the failure of maximum biofloc systems. In order to solve the main problem, Multinational Aqua Research Centre provide 6 months online support to their students to carryout the biofloc based farming for at least one crop. In this trainings support module, the registered participants will get the following knowledge and skills:

  1. Basic concept of different Aquaculture System
  2. Fundamentals of Biofloc based farming System
  3. How to Construct Biofloc tanks?
  4. How to Start the Culture?
  5. How to monitor the System?
  6. What are the different types of Fish Diseases occur in Biofloc?
  7. How to do trouble shootings?
  8. How to harvest the stocks?
  9. How to manage the system during disease out break?
  10. Best management Practice for Biofloc System

Please feel free to contact us for training support.

Multinational Aqua Research Centre
Abhoynagar, Agartala, Tripura (W)-799005, India
Mob: 07005820412

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