SUSTAINABLE SHRIMP & FISH CULTURE WITH BIOFLOC TECHNOLOGY

Recent advances in super-intensive, limited-discharge, biofloc systems for the culture of Litopenaeus vannamei, suggest that these systems can be profitable in farming. These systems offer improved biosecurity with reduced risk of crop losses to viral disease outbreaks. Furthermore, operating these systems with no water exchange minimizes the negative effluent impact on receiving waters.

Implementing biofloc technology to culture shrimp in ponds and reticulating systems could offer several advantages, including improvement of water quality and animal nutrition. There are two primary biofloc technology systems that can be considered for shrimp culture. The first are in-situ biofloc systems, where biofloc form in the culture pond/tank along with the shrimp. The second are ex-situ biofloc systems, in which effluent waters are diverted into a suspended-growth biological reactor where biofloc are generated and subsequently can be used as an ingredient in shrimp feed. In-situ systems are currently in use, and ex-situ systems are in the developmental stage.

Each option (in-situ versus ex-situ) has unique benefits and limitations. For example, in-situ biofloc systems, under proper conditions, can assimilate ammonia directly into microbial proteins, thereby preventing the accumulation of nitrate (from nitrification). Additional benefits are that the biofloc provide nutrition directly to the shrimp. However, the downside is lack of control regarding manipulation of biofloc nutritional profiles. Furthermore, in-situ biofloc systems exert a high oxygen demand because oxygen is being used by both biofloc and shrimp. With ex situ biofloc systems, one has better control of floc nutritional profiles and can manage the demand for oxygen by floc and shrimp in separate tanks.

Biofloc are a consortium of microorganisms, micro/macro invertebrates, filamentous organisms, exocellular polymers, and uneaten feed. This nutritious mixture has often proven to be beneficial for shrimp production. When biofloc are included in shrimp diets, either directly from the water column or in a processed feed, shrimp often exhibit positive responses such as improved health and growth rates. Biofloc might also reduce the amount of feed required and/or replace a particular ingredient (e.g., some biofloc are rich in proteins and can be used to replace expensive marine meals). Biofloc nutritional composition varies greatly depending on many variables, including sunlight, temperature, salinity, nutrient loading, carbon supplementation, residence times, oxygen levels, etc. In some cases, these variables can be controlled and can influence the nutritional profiles of biofloc.

Geekay Hatcheries has experience implementing biofloc systems in Indian conditions and improves upon this technology by applying aerotube aeration systems to  decrease costs and increase yield, in a sustainable environment friendly system.