Biofloc Fish Farming

Biofloc technology improves water quality in fish tanks by balancing carbon and nitrogen in the water. Adding a carbon source (such as molasses or flour) lets heterotrophic bacteria take up the ammonia from fish waste and uneaten feed, and the bacteria clump together with algae and organic particles into “flocs” that the fish can eat. The method was developed for intensive fish production in a small area, as an alternative to open ponds, and because little or no water is exchanged, it also reduces the risk of bringing disease in with new water.

In India, demand for fish from aquaculture is rising with the population, and India produces about 8% of the world’s fish. Two things limit the growth of conventional aquaculture: waste discharged from farms pollutes water bodies, and farms depend on feed made from fish meal and fish oil.

Biofloc addresses both. The water is treated inside the tank instead of being discharged, and the flocs are a protein-rich feed produced in place, which reduces the amount of bought-in feed. In effect, a biofloc tank is a wastewater treatment system that also feeds the fish.

Requirement for Biofloc technology: 

Fish is a major source of food and of employment. Demand is growing for fish to eat and for fish used by industry to make fish meal and fish oil, and it grows with the population.

Traditional pond farming needs a lot of land and water to meet that demand. Biofloc lets farmers raise more fish in less space with less water exchange, which makes it attractive for small farmers in India who earn their living from fish farming but cannot afford the land, water or feed costs of traditional ponds.

Growth performance in Biofloc system:

In biofloc trials, fish growth is tracked by measuring length and weight every 15 days. A typical method is to take 10 fish at random from each treatment replicate and weigh them, after starving them overnight so that gut contents do not affect the weight.

Length is measured with a measuring scale and weight with an electronic balance. Growth performance is then calculated from parameters such as specific growth rate (SGR), percentage weight gain (PWG), feed conversion ratio (FCR), protein efficiency ratio (PER), biomass and survival rate.

Top 3 Materials Required For Biofloc Farming

Some of the materials are easy to buy anywhere; others are sold mainly through aquaculture suppliers. The essential items to start biofloc fish farming are:

1. Tanks

The first requirement is the fish tank. Many farmers use a circular frame tank with a waterproof liner, such as a PVC tarpaulin or HDPE sheet; others build the base and walls from bricks, sand and cement. Either way, the floor should slope to a central outlet.

2. Outlet

The outlet controls the water level and lets sludge be drained from the bottom of the tank. It is fitted at the base of the tank with pipes, so excess water can be released and the tank can be drained for harvesting.

3. Oxygen Supplier (Tank)

Aeration is the most important item. A biofloc tank holds a large number of fish in a small volume, and the bacteria that form the flocs also use oxygen, so the dissolved oxygen in still water is not enough. An air pump or blower with diffusers runs continuously to supply oxygen and to keep the flocs suspended. Because a power cut can kill the stock within hours, a backup power supply is needed.

Conclusion

Biofloc turns toxic fish waste into protein-rich feed and can raise production from a small area with little water exchange. It is still a developing technology, and it can be combined with other food production in integrated systems that produce more food and feed from the same land with fewer inputs. The approach is also known by other names, such as zero-exchange aerobic heterotrophic (ZEAH) culture and single-cell protein production systems (SPPS).

Biofloc needs more management than a pond: continuous aeration, a reliable carbon source, and regular checks on ammonia, dissolved oxygen and floc volume. Farmers who plan for these can raise production and profit.