Biofloc Technology Aquaculture System:
Today, let us get into details of Biofloc Technology Aquaculture.
Biofloc system is a technology in which the materials which are harmful and poisonous to the fish or shrimp are transformed into some protein food. This is basically used in aqua farming when the density of stocking is high with very less exchange of water. This method would be run productively when the tanks used are kept in direct sunlight.
This has been introduced and developed in order to increase the regulation of the environment in aqua farming. The main factors which influence the aqua farming are the cost of feed and the availability of space. If the stocking has to take place at high density, then the wastewater should be treated on a higher basis. Biofloc system is the one which has been brought into existence and was given more importance only in order to treat the wastewater in aqua farming.
Use of Biofloc Culture:
In Biofloc system, the nutrients and the wastes occurred from nitrogen are recycled. The recycling is done by keeping the ratio of nitrogen and carbon dioxide at high levels in the water. These are maintained at high levels for the stimulation of bacteria which are heterotrophic. The growth of bacteria will be enhanced when the sources of carbon dioxide like cellulose or molasses are kept in the pond with continuous circulation of air. By the maintenance of the ratio of carbon and nitrogen by the addition of sources of carbon, the production of the microbial protein with high quality is done. Through Biofloc systems, the water quality increases. Along with the quality of water, there would be the availability of a very good nutrition source to the fish or shrimp, which helps them in their healthy growth and increases their resistance to diseases. This method can be implemented after checking the pH levels of water along with temperature, levels of oxygen which are dissolved etc.
The main motto of this system is to generate the cycle of nitrogen by having a Carbon and nitrogen ratio at a higher rate by encouraging the growth of microbes which is heterotrophic. This absorbs the wastes of nitrogen, which can be damaged by the cultured species as they take it as a food.
When the ratio of carbon and nitrogen are maintained at high rates, then the microorganisms will be developed in more numbers and work in controlling the quality of water and the food source. The fixation of nitrogen species which are poisonous will be done quickly in the Biofloc systems. This is because the growth of microbes will be ten times more than that of the bacteria which are autotrophic.
This system is used in the production of shrimps as it dwells at the bottom of the water and is very adaptable to the changes in the environment. Compared to other traditional practices, Biofloc proved to improve the production of shrimps.
Nutritional Composition of Biofloc Technology Aquaculture System
Biofloc system contains up to 40% to 50% of protein, 5% of lipids, 7% of fibre, 20 kJ/g of energy. The level of proteins in this system is completely dependent on the crude protein which is present in the food and the sources of carbon. There would be 30% of polyunsaturated fatty acids, 30% of monounsaturated fatty acids and 35% of saturated fatty acids. There would be approximately 110 bacteria in number for 1 ml of floc. Though it has a rich amount of proteins, there needs some supplementary feed to adjust the volume of the Biofloc system.
Shrimp and Fish Biofloc Technology Aquaculture System:
- In order to develop the Biofloc system for fish and shrimp, make sure you are starting within lined ponds.
- Before going to the next step of stocking, you need to add organic matter to the pond like molasses etc.
- Then add Nitrogen at a level of 2 mg per litre of water.
- In order to get the Biofloc system developed, you need to wait for some weeks. When the Biofloc system is forming, then there would be some sort of algae forming at the first stage, then transition takes place with the formation of foam. Then the algae turns brown in color.
- In Tilapia fish, the transition will be done rapidly. But in shrimp, it takes much time.
- You can add seeding in the form of clay which will help in the formation of Biofloc.
|Protein content in feed
|Carbon and Nitrogen content in feed
- The Biofloc which is applied in the tank which rears the shrimp or fish is a dynamic method. The feed and the support which has to be given for the shrimp Biofloc systems is mentioned below.
- The main component for the Biofloc culture is the heterotrophic bacteria.
- The Biofloc system works to decrease the waste produced from nitrogen like ammonia, which is being produced while the shrimp is getting fed or produced.
- The content of ammonia, which will be taken by the heterotrophic bacteria will be taken by the shrimp as a feed which helps in its growth.
- Carbon is required for the heterotrophic bacteria for the absorption of ammonia. There should also be a supplementary source of carbon along with the commercial feed to improve the production of heterotrophic bacteria and decrease the wastes of nitrogen.
- The feed which is given to the shrimp in Biofloc will have carbon and nitrogen ratio of 10:1. This ratio will be 14:1 for heterotrophic bacteria. In order to enhance the ratio of carbon and nitrogen, few basic sugars are added so that the growth of bacteria will be increased.
- Even carbon contents like molasses are also used to increase bacterial growth. Few shrimp production systems use glycerin to raise the levels of bacterial growth. The more simple the quality of sugar, there would be more response from the heterotrophic bacteria in terms of growth.
- The amounts which have to be applied will be changed as per the content of the protein in the food and the carbon composition. Generally, for 2 kgs of feed, there would be 1.5 kg of carbon amount needed.
- If the feed has a high amount of protein, then there would be more amounts of carbon, which should be given as a supplement.
- The addition of oxygen should also be a part of a Biofloc system in order to stop it from getting suspended. Without mixing the oxygen, the bacterias will get sunk and their ability to lose the content of ammonia will be decreased.
- The process of mixing will be done by using airlifts, water pumps and diffusers. The aeration will be done based on the production of the shrimp. If the level of production is more, then, oxygen supplied must be pure in content.
- If the rate of respiration of the Biofloc is more, then there would be a high amount of carbon dioxide produced.
- The methods of aeration can remove carbon dioxide from the water. But, the carbon dioxide which is removed will be raised in the environment. This is again completely dependent on the content of the air exchanged.
- If the rate of feed is high, then there would be an increase in the population of Biofloc which will cause harm to the shrimp.
- The solids which are suspended more than 450 mg/litre will cause stress to the shrimp and their gills will get some kind of irritation. So the total suspended solids should be regulated by fractionation of foam or by using basic clarifiers.
- By using such type of devices, the total suspended solids can be regulated by the rate of flow of the water through the devices. The solids can be regulated by changing water from the tank for every three days. The size of the clarifiers is set in such a way that it contains a volume of 5% and a good flow rate.
- When the total suspended solids are removed, then the alkaline nature and the nitrate will also be removed from the system.
- You can get back alkalinity making the sediments to undergo anaerobic decomposition. By taking off the solids from the system, nitrates can be removed.
- By using the method of anaerobic decomposition, nitrate can be removed by converting into nitrogen gas, which will then be allowed into the environment.
- But for Anaerobic decomposition to take place, it needs a very good space. In the simple method of anaerobic decomposition, some portion of the Biofloc system will be occupied due to the formation of sludge. Then it is allowed to be free of oxygen for some time and removed.
- But only a small part of alkalinity attached to the heterotrophic bacteria will be retained by the using the method of anaerobic decomposition. This alkalinity should be replaced with sodium bicarbonate.
- The alkaline level should be maintained at 145 mg per litre and should be checked for two to three times a week. The pH level should be maintained at 6.5 to 7.
Read: Backyard Fish Farming Guide.
Evaluation for Biofloc Technology Aquaculture System:
- The Bioflocs should be monitored for every half an hour.
- The solids can be monitored by using Imhoff cones which are used to measure the suspended soil contents.
- In shrimp production, it should be 35 ml per litre and in fish production, the TSS should be 90 ml per litre.
- It is always important to make sure that the total suspended soils are not more than 200 ml per litre.
- If you find that the content of ammonium is high, then try to decrease the content of protein in the feed you provide for the fish or shrimp.
- It is very important to respond to the changes in the Biofloc systems immediately.
- If the amount of nitrite is high, then you need to check if the oxygen content is low, try to accumulate the sludge and place an aerator for the circulation of oxygen.
- If the volume of the floc is low, then you need to add carbon.
- If the volume of the floc is high, then you need to drain all the water out.
Advantages of Biofloc Technology Aquaculture System:
- Biofloc system is environment-friendly as it as no bad effects on the environment.
- The usage of water and the area would be improved.
- The exchange of water will be less.
- It improved the survival rate of the fish, thereby increasing the production.
- It follows the procedures which are designed to save the species from harmful biological substances.
- Water will be saved from pollution and there would be no pathogens growing in the water.
- The production of feed will take less cost.
- The feed which is rich in proteins can be used less which thereby decreases the feed cost.
Disadvantages of Biofloc system:
- For the purpose of mixing and the circulation of air, there would be more levels of energy required.
- Because of the increase in the respiration rates in water, the rate of response will decrease.
- It takes some time to start the process and its execution.
- The alkaline content should be supplemented.
- Due to the gathering of nitrate content, there would be an increase in the pollution.
- For the systems which are exposed to sunlight, the results might not be consistent.
Read: Raising Catfish In Tanks.