At densities ranging from 250 to 500 post-larvae (PLs) per square meter, shrimp are stocked in biofloc systems. These systems may produce 3–7 kg/m2 or 3–9 kg/m3 of product. Feed conversions ought to be between 1.2:1 and 1.6:1. For every unit of commercial feed, microbial proteins in the biofloc typically add 0.25 to 0.5 more growth units. Table 2 displays the production parameters for various systems.
Shrimp are kept in single batches of postlarvae of the same size (PLs). Based on calculations of biomass, feed conversion, mortality, individual weekly gains, and percentage body weight feeding, feeding is done.
One and a half hours after feeding, the feed rate is adjusted following routine sample for uneaten feed on the tank bottom using a dip net. Unsatisfactory feed parameters can also be indicated by subpar water quality parameters. Feed can be distributed manually or mechanically, using a belt feeder, for example. The ideal method of feeding is by hand since it allows you to cover a large area of the tank and ensure that every animal gets food. It is possible to use automated feeders without an operator present. Even in a biofloc system, processed feed is still the most crucial ingredient for excellent shrimp growth. A reliable manufacturer should be used to obtain and store shrimp feed.
As the shrimp age, their diets shift, and the size of the pellets rises from about 1.5 mm to 2.5 mm. The ratio of protein to fat may stay at 40:9 throughout the growth season. A smaller particle size and a greater protein feed are necessary if PLs are smaller than suggested. Please inquire about suggested beginning feeds from feed and PL suppliers.
The following is an illustration of how to calculate the daily feed allowance:
A 16-foot pool that is about 3 feet deep is supplied with 300 PLs, with an average size of 1 g. After four weeks, how much would the daily feed allowance be? The theoretical biomass of shrimp is calculated using the numbers from Table 2.
We can get 6,000 shrimp at 7 g apiece, or 42,000 g or 42 kg, by stocking 300 shrimp per m2 in 20 m2.
In week four, feeding at 4% of body weight would require 37,800 g multiplied by 0.04 to equal 1,512 g, or 1.51 kg.
Feed can be given continuously or over the course of several feedings each day. The decision has to do with managerial style and mechanization. Due to their short intestines, shrimp should be fed in modest amounts throughout the day or continuously. Multiple feedings each day increase the efficiency and consistency of biological waste treatment operations.
Management of biofloc in shrimp aquaculture
It is necessary to treat the Biofloc in the shrimp-rearing tank as a dynamic living organism and to manage it accordingly. Heterotrophic bacteria are the core component of Biofloc. The Biofloc system’s purpose is to lessen the nitrogenous metabolic waste (ammonia, nitrite) generated by shrimp production and feeding. In a shrimp Biofloc system with a 10,000 cubic meter capacity and an FCR of 1.3, it is expected that a feed containing 35 percent crude protein or 5.6 percent nitrogen is applied at a rate of 400 kg per day.
Heterotrophic bacteria use ammonia to produce protein, which shrimp can eat to fuel their growth. For heterotrophic bacteria to absorb ammonia, carbon is necessary. To promote the growth of the heterotrophic bacteria and lessen the nitrogenous waste, more carbon should be supplied to the commercial feed.
The carbon to nitrogen (C: N) ratio in shrimp feed ranges from 7 to 10. A ratio of roughly 12:1 to 1 would be preferred for heterotrophic bacteria. The ratio is raised and bacterial growth is encouraged by the addition of simple sugars or starches. Molasses, sugar, sucrose, and dextrose have all been used as additives in the past. Some companies also utilize glycerin. The simpler the sugar, the quicker the response from the bacteria. Application rates will vary depending on the protein level of the feed and the carbon source’s composition, but as a general guideline, 0.5 to 1 kilogram of carbon source is needed for every 1 kg of feed. More carbon will need to be added to feed that contains more protein. The concentrations of ammonia and nitrites in the water should be taken into account for actual applications.
The primary factors influencing the selection of a carbon source are cost, availability, practicality, and effectiveness. No matter the physical state, the carbon source must be diluted before application. The necessity to maintain Biofloc in suspension can be paired with the supply of oxygen. Colonies of heterotrophic bacteria will sink without mixing, and they will subsequently stop being able to remove ammonia. Airlifts, diffuser stones, and water pumps—the same tools used to deliver oxygen—are used to mix substances. The amount of production and equipment centralization influence the decision between aeration and oxygenation techniques. It may be necessary to replenish with pure oxygen when production levels are high. Multiple tanks powering airlifts and diffusers can be served by low-pressure, high-volume air blowers of various sizes. The same is true for water pumps, which can power numerous venturi aspirators yet are designed for single huge tanks.
Settled solids in shrimp biofloc should remain between 10 and 15 mg/l.
Production of fish (tilapia) in little concrete tanks should range from 20 to 40 kg/m3.
10000 L BIOFloc Tarpaulin Tank Setup
Let’s set up a BIOFloc Tarpaulin Tank, and to do that you need to be familiar with the following information:
- Tank Volume 12,000 L
- 4 meter tank diameter
- Circumference of GI Mess: 12.56 meters (Buy 13 Meter)
- 1.2 m for the GI Mess
- Size of Tarp4 Diameter
- Height of Tarp 1.3 meters
- 12.57 meter circumference of the tarp
- One drain pipe (3 Inch)
- 1 PCS Drain Pipe L Connector (3 Inch)
- 1 PCS Drain Pipe Stopper (3 Inch)
Make the surface plain and choose a location without water logging. 5 x 5 meters of space are needed to set up one 10,000 L BioFloc tank.
Step 3: To make the slug exit, a 3-inch PVC drainage pipe needs to be installed in the middle. To achieve it, dig as shown in the image from the circle’s center to install 3 inch PVC pipe.
Cement should be applied to the L-Shape 3 inch PVC Connector to assist stop the pipe from moving.
As indicated below, a central control unit should be linked to 3 inch drain PVC pipe.
For optimal water drainage, have the drainage pipe sloping away from the center by about 1.5 feet.
All of the drainage lines from the tanks are connected to this central control room.
Step 4: Dish In order for the Tarpaulin Round Cover to fit into it effectively, the circumference must be 12.56 meters. Make a 13-meter piece of material, and attach it appropriately to get a circle that is 12.56 meters in diameter. Once the mess has been correctly rounded, make sure the bottom and top are both 4 diameter. Paint the mess to prevent corrosion.
Step 5: Add sand to the middle and create the necessary slope thereto as indicated below. 1.5 feet of slope is ideal for better water drainage, in my opinion.
Step 6: To prevent rust, place the mess on top of the brick and cover the bottom of the mess with cement.
Step 7: After the mess is ready, the tank should be covered with a fiber/aluminum sheet for protection. In essence, it aids in shielding the tarp from harm from the outside world.
Step 8: By spreading polythene on the tank’s bottom, we are adding one more layer of defense. Because greater investment is needed, it’s once more a matter of personal preference.
Step 9: The finished result does not include the iron mess since the sharp spikes could harm the tarpaulin. We need to conceal these edges.
Therefore, to hide these edges, we are utilizing bicycle tires, which are available for free from any bicycle repair shop.
Step 10: We are now prepared to install the 10,000 liter tarp tank. Open the tarpaulin tank, which should be evenly distributed inside.
To hold the circular tarpaulin tank securely, grab any piece of it and place it on the wire mesh.
When the tarpaulin tank is properly set up, it should seem like in the picture below.
The tarpaulin tank should resemble the image below once the rope has been suitably tightened.
Install the central drainage line after the Tarpaulin Tank has been put up correctly. Make sure the central drainage line is not leaking.
Quality of Water and Biofloc
In addition to providing nutrients, biofloc can be controlled to enhance the water quality in culture tanks.
Autotrophs and heterotrophs are the two main categories of microbes found in these systems. Autotrophs are living things that convert inorganic substances into organic ones. Inorganic carbon sources like carbon dioxide and bicarbonate are where they get their carbon. They can also be divided into two groups: chemoautotrophs, which get their energy from inorganic chemicals, and photoautotrophs, which get their energy from sunshine. The former are algae in aquatic conditions, whereas the later are bacteria like nitrifiers that get their energy by oxidizing ammonia to nitrate. On the other hand, heterotrophs get their carbon from organic carbon sources.
By consuming toxic to shrimp dissolved inorganic nitrogen molecules including ammonia, nitrite, and nitrate, both autotrophs and heterotrophs present in biofloc increase water quality. To do this, it is possible to manipulate a biofloc-dominated system to promote autotrophic, heterotrophic, or a mix of the two types of bacteria.
What percentage of Biofloc is shrimp?
Stocking and feeding shrimp In biofloc systems, shrimp are stocked at densities of 250 to 500 post-larvae (PLs) per square meter.
In biofloc, can shrimp be grown?
Mahendrapalli, a little village on the banks of the Pazhayar about 18 km from Kollidam, is dotted with shrimp ponds that are lined with High-Density Polyethylene (HDPE).
On his enormous farm, Suryakumar Boriah is quietly working on biofloc, an environmentally benign, disease-resistant shrimp farming method. An ecologically viable symbiotic system, Biofloc is a beneficial bacterial colony-based culture that prevents the spread of other bacterial illnesses. The traditional plankton-based shrimp cultivation, which frequently keeps farmers on edge owing to the risk of disease outbreak, is different from biofloc shrimp farming.
Mr. Suryakumar is one of the few farmers in the nation who has been using biofloc since 2011, owning the sole farm of its sort in the State.
Biofloc is environmentally beneficial because it exchanges no water. According to Mr. Suryakumar, pH and nitrogen levels in water are the main issues with shrimp culture. The bioflocs, which eat the nitrogen the shrimps create, maintain a constant pH level in the water. “To keep livestock stress- and disease-free, nitrogen is flushed out by water exchange every 25 to 30 days in conventional farming. The bioflocs soak up the nitrogen and transform it into proteins, for the shrimps,” adds Mr. Suryakumar. Artificial probiotics for animals are reduced as a result. Water exchange has historically been a source of conflict between shrimp farms and nearby landowners.
The manager of Suryakumar’s farm, Govindaraj, explains that the animals are protected from illnesses by the tightly HDP-lined ponds. A biofloc pond costs roughly Rs. 14 lakh per hectare, which is three times what a regular pond costs. However, the advantages of the system outweigh the financial expenditure. “There is no dry season, and the ponds are always suitable for crop production. The HDP linings are intact for five years,” adds Mr. Govindaraj. Shrimp meal consumption is decreased because to Biofloc. The ultimate objective, according to Mr. Suryakumar, is to reduce the food conversion ratio to 800 gm of fishmeal to create 1 kilogram of shrimp (FCR 0.8:1).
In the biofloc system, production is high per unit of land. A biofloc pond produces 20–30 tonnes per hectare as opposed to 10-15 tonnes in a typical pond.
In a biofloc pond with HDP lining, animal stocking density is double that of a typical shrimp pond.
Mr. Suryakumar acquired the method from Yoram Avnimelech, who is credited for developing the Tilapea fish rearing technology. Professor Yoram, who is in charge of the International Working Group on Biofloc Technology, has written about Mr. Suryakumar’s advancements in biofloc shrimp growth.
But there are still barriers to using biofloc. According to Mr. Suryakumar, this method needs an ongoing supply of oxygen from aerators, a capital subsidy from the Marine Products Exports Development Authority, demo farms for exposure, and institutional assistance for farmers.
Additionally, according to Mr. Suryakumar, the Coastal Aquaculture Authority’s regulations on the maximum stocking density of ponds and general excise limits on the use of molasses as a carbon source need to be updated for licensed farmers. Kandan, Assistant Director, MPEDA, claims that it is an inversion of conventional wisdom. In the past, ponds were permitted to grow moss as fish food. Biofloc uses the same approach. Biofloc shrimp ponds ring in a glimmer of hope, if there is institutional support for farmers, at a time when the nation’s shrimp industry is on the verge of a probable EMS (early mortality syndrome) outbreak.