Site selection is vitally important since it can greatly influence economic viability by determining capital outlay, by affecting running costs, rate of production and mortality factors. The stocking density and size of stocked fishes varies with different species. It is an innovative and cost-effective technology in which toxic materials to the fish and shellfish such as Nitrate, Nitrite, Ammonia can be converted to useful product, ie. It is the technology used in aquaculture system with limited or zero water exchange under high stocking density, strong aeration and biota formed by biofloc.
The culture of biofloc will be productive in the case of culture tanks exposed to sun. Biofloc system — the need Biofloc system was developed to improve the environmental control over the aquatic animal production. High stocking density and rearing of aquatic animals requires wastewater treatment. Biofloc system is a wastewater treatment which has gained vital importance as an approach in aquaculture. The principle of this technique is the generation of nitrogen cycle by maintaining higher C: N ratio through stimulating heterotrophic microbial growth, which assimilates the nitrogenous waste that can be exploited by the cultured spices as a feed.
The biofloc technology is not only effective in treating the waste but also grants nutrition to the aquatic animal. The higher C : N is maintained through the addition of carbohydrate source molasses and the water quality is improved through the production of high quality single cell microbial protein. In such condition, dense microorganisms develop and function both as bioreactor controlling water quality and protein food source.
Immobilization of toxic nitrogen species occurs more rapidly in bioflocs because the growth rate and microbial production per unit substrate of heterotrophs are ten-times greater than that of the autotrophic nitrifying bacteria.
This technology is based on the principle of flocculation within the system. The biofloc technology has been implemented in shrimp farming due to its bottom dwelling habit and resistance to environmental changes. Studies have been conducted to assess the larval growth and reproductive performance of shrimps and Nile tilapia. An improved breeding performance was observed in shrimp reared in the biofloc system when compared to that of normal culture practices.
Similarly improved larval growth performance was also noticed. Composition and nutritional value of biofloc Biofloc is a heterogeneous aggregate of suspended particles and variety of microorganisms associated with extracellular polymeric substances. It is composed of microorganisms such as bacteria, algae, fungi, invertebrates and detritus, etc.
It is a protein-rich live feed formed as a result of conversion of unused feed and excreta into a natural food in a culture system on exposure to sunlight. Each floc is held together in a loose matrix of mucus that is secreted by bacteria and bound by filamentous microorganisms or electrostatic attraction.
Large flocs can be seen with the naked eye, but most of them are microscopic. Floc size range from 50 — microns. A good nutritional value is found in biofloc. The dry weight protein ranges from 25 — 50 percent, fat ranges 0. It is a good source of vitamins and minerals, particularly phosphorous. It also has an effect similar to probiotics.
The dried biofloc is proposed as an ingredient to replace the fishmeal or soybean in the feed. The nutritional quality is good; however, only limited qualities are available. Furthermore, the cost-effectiveness of producing and drying biofloc solids at a commercial scale is a challenge.
September 27, September 27, February 12, February 12, January 9, January 9, Download Free PDF. Types of aquaculture Karri Rama Rao. A short summary of this paper. Download Download PDF. Translate PDF. Rama Rao Types of Aquaculture I. Depending on Hydrobiological Features: Depending on hydrobiological features aquaculture is divided into following: a Freshwater, b Brackish water, c Metahaline, and d Mariculture. Various types of culture practices are carried out in each of these divisions Fig.
They are as follows: i Composite fish culture or polyculture or mixed fish farming: Fast growing compatible species of fishes with different feeding habits are cultured together. Karri Rama Rao, Dept. By this method the yield can be enhanced.
Here, predator fish like murrels are cultured along with their prey- fish, tilapia. Such tanks can be utilised for the culture of fishes such as common carp, murrel, tilapia, catfishes, etc. Such water contains high nutrients which are responsible for production of plankton bloom, the food of fishes.
Hence, water is circulated continuously through a biological filter. These fishes help to control the vectors mosquito, etc.
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