ULTRA INTENSIVE AQUACULTURE SYSTEM

Pradeep KumarP. Gangeswari andM. Venkatasamy

Fisheries College and Research InstituteTamil Nadu Veterinary and Animal Sciences University

Thoothukudi-628 008

Ultra intensive aquaculture systems are opposite to the extensive culture systems.

If the extensive fish culture ponds are considered as natural ecosystems, then the

ultra intensive culture systems are considered as factories. The ultra intensive culture

systems are slightly more than culture vessels through which energy is passed under the

close attention of technicians. These factories manufacture large amounts of aqua

products on very small areas. Ultra or Super intensive aqua farming takes even greater

control of the environment and can produce very higher yields. In poultry farming, the

production technology has been turned into a big business through simultaneous advent

of genetic manipulation on one hand and broiler house on the other. With this vision and

an objective of massive aquatic protein production, almost all aquaculturists dream of the

day when an aquatic broiler house will be achieved through the super intensive culture of

desirable aquatic animals which will be brought almost entirely under human control.

CONCEPT

In general, the super intensive aquaculture is practiced in a system where extreme

care will be taken towards the cultivable species by minimizing the external and internal

biological, physical, chemical and or environmental stresses to zero level in such a way

that the stock attains maximum harvestable size in a short span of time. This system,-

applies the broiler house concept that is so prevalent and effectively used in

modern poultry production systems to rear large number of fish in a relatively

small space;

provides environmental control for optimum year round growing conditions;

eliminates predators;

prevents and or controls diseases;

protects from external influences including contamination through pollution and

from natural catastrophies;

works on acceptable waste disposal procedure; and

adopts manipulated technology suitable for temperate and tropical plains.

SYSTEM

Two basic requirements are needed for culturing any species under super

intensive culture conditions. The first is the knowledge on the environmental

requirements of the selected species, somewhat more detailed than that is required for

other culture types. The second is a detailed knowledge on the complete nutritional

requirements, which is not required in extensive culture type. The entire culture

technique has the following two categories:

i) The Components.

ii) The Technique.

Components

A generalized super intensive system contains three major components, such as,-

a) Culture vessel.

b) Filtration.

c) Force.

The inputs to the system include food, heat and oxygen.

Culture vessel

It is important to generalize that the tank is merely a vessel to contain the aquatic

organisms and accessories. The maximum size will also be limited by the ability to

control the water quality.

Filtration

Water treatment can be operated in three stages. The first stage consists of particle

removal. The purpose of this stage is to deliver the water so that a biological bed free of

suspended material is formed. This is important for long and trouble free operation of the

biological filter. The second stage represents the biological filter. Its bed contains

sufficient number of bacteria (i.e., area of bacterial substrate) to oxidize nitrogenous

waste to which it will be subjected. The design and operation is such that the bed is

always abundantly supplied with oxygen. Determining the required volume of a

biological filter is something less than a science of the present time. High flow rates are

important in supplying oxygen to the bacterial bed. The third stage represents additional

treatment methods available including foam fraction, ultra filtration with ozone etc.,

Treatment at this stage is generally expensive.

Force

This represents any equipment needed for water movement. The energy source is

immaterial, so long as sufficient flow rate is maintained. Electrical pumps are the choice

of the majority, with air lift running system.

Inputs

Feeding

Commercial feeding services are available which are directly applicable or

converted to super intensive culture system of any species.

Heating

For tropical organisms, warm temperature is required and it can be fulfilled by

solar, geothermal and waste heat from industrial source.

Oxygenation

Probably the single most important factor in the super intensive culture system is

the maintenance of oxygen content of culture water. Methods of supplemental

oxygenation range from simple bubbling of atmospheric air to sophisticated systems for

injuring liquid oxygen.

Technique

The Recirculatory Aquaculture System (RAS) represents a new ultra intensive

culture technique to farm fish. Instead of traditional method of growing fish outdoors in

open ponds, this system rears fish in high densities, in indoor tanks with a controlled

environment. New water is added to tanks only to make up for splash out and

evaporation and for that used to remove waste materials. A biofilter system is necessary

to purity the water and to remove or detoxify harmful waste products and uneaten feed.

The fish must be fed with a nutritionally complete feed, on a daily basis to encourage fast

growth and high survival. Only in the past few years, the potential of RAS to grow fish

on commercial scale has been realized. Efficient water quality testing instrumentation

enhanced with computer monitoring program designs will be of much useful, if

developed and incorporated exclusively for this industry to make revolution in tank fish

culture.

RAS can be of various sizes ranging from large scale production system(over

million kgs per year) to intermediate sized system (500,000 kgs per year) to small system

(50,000 kgs per year). They can be used as grow out systems to produce food fish or as

hatcheries to produce fry and fingerlings, sport fish for stocking and ornamental fish for

home aquaria.

The biological filter is the heart of RAS. As the name implies, it is a living filter

composed of a media (corrugated plastic sheets or beds of sand grains) upon which a film

of bacteria grows. The bacteria treat wastewater by removing the pollutants of two

primary water pollutants that need to be removed including the fish waste (toxic

ammonia compounds) excreted into water and the uneaten fish feed particles. The

biofilter is the site where beneficial bacteria remove or detoxify the fish excretory

products, primary the ammonia. The biofilter in super intensive RAS design must be

sized to correspond with other system components. Important factors that must be

considered in designing a biofilter include,-

i) Media surface area ( for bacteria attachment);

ii) Ammonia loading ( that need to be converted per day per unit of media area);

and

iii) Hydraulic loading ( per day per unit of media surface).

The two general filter categories are the submerged bed filter and the emerged

bed filters (trickling filter and rotating biological filter).

RAS offers fish producers a variety of important advantages over open pond

culture. These include a method to maximize production on a limited supply of water and

level and area, nearly complete environmental control to maximize fish growth year

round, the flexibility to locate production facilities near large markets, complete and

convenient harvesting and quick and effective disease control.

PROSPECTS

The long term demand for aquaculture products is excellent. An increasing human

population especially the older adults, who proportionally eat more fish than youth and

an increasing public awareness about the importance of fish in diets and human health

and fitness are driving upwards the fish consumption. Correspondingly, the prospects for

ultra intensive farming of finfish and shellfish are good. A number of experts believe that

the future trends in aquaculture industry are towards this type of farming. Growing fish in

indoor tanks is analogous to rearing poultry in confinement or feed lot system. Open

pasture system has proved to be less efficient in the farming of most farm food animals

than confinement system and this will very well be true also for rearing fish.

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