Technical Guide for Tilapia Farming (CDI, 1998, 51 p.)
PART THREE: FISH FARMING EQUIPMENT AND RECOMMENDED EUROPEAN SUPPLIERS
Fish farming equipment[edit | edit source]
The equipment requirements of a project depend largely on the type of rearing to be done and the level of production envisaged. The degree of the use of automation needs to fit within the global context of the project.
Pumping[edit | edit source]
When it is not possible to have a water supply by gravity, pumping needs to be studied. It is not advised, at this time, to implement an intensive fish farm in tropical countries on a site where pumping is required; for an intensive commercial production (300/400 tonne per year), a flow exceeding 1,000 m3/h will be necessary. When pumping is necessary, it is more appropriate to consider extensive or semi-intensive farming under tropical conditions
Water needs for extensive systems are not so high as for the other alternatives described. In these conditions, the water supply should compensate the water lost through evaporation and infiltration into the soil. In a semi-intensive system, a water exchange of 15 to 25% per day has to be accounted for.
In order to evaluate exact pumping needs, the calculation will be based on the water requirements of the rearing system, the size of the ponds, on the soil nature (losses through infiltration) and also the climate (rainfall and evaporative loss). Each case demands a specific study that will determine the type of pumps to be used and their capacity.
Harvest[edit | edit source]
The equipment for this is the basic (and most used) equipment in fish farming. Nets for harvest must be adapted to the facilities (i.e. the size and depth of ponds). Large mesh nets must be used for harvesting bigger fish while small mesh nets must be foreseen for fry. Nets must be well maintained and be checked after each use, in order to maintain an efficient standard of operation. Not only the condition of the mesh but also floats and ballast must be subject to constant checks.
Aeration[edit | edit source]
There are two main types of aeration systems used in commercial aquaculture.
Aeration by pulsed air: A blower generates air at relatively low pressure through pipes to air stones or other diffusers. This system is particularly well adapted to small-scale facilities and for fry and small fish since it does not cause damage due to water turbulence.
Aeration by mechanical agitation: There are many different types of aerators (fountain aerator, paddlewheel, and Venturi system) and each has strong and weak points.
- Fountain aerators suck the water from the bottom of the pond and throw it into the air as a fountain. This is done very simply by the use of a motor-driven propeller. It is a very efficient aeration system because it takes the water from the bottom that is poor in O2 and creates an important water movement within the pond. The main disadvantage is that it creates waves that can damage the dams of the ponds by erosion and a build-up of heavy silt underneath the aerator, imposing maintenance of the pond structure at regular intervals.
- Paddle wheel aerators use motor-driven paddles on floats to throw the water into the air for aeration and create a movement on the surface of the pond. While these might be not seen to be so efficient as the fountain aerator, on the other hand, they offer the advantage of creating less erosion and of not creating turbidity.
- The aerators equipped with a Venturi system are also very efficient because the system creates an important aeration effect and induces a good gaseous exchange. They can sometimes cause turbidity and create a hole on the bottom of the pond if the flow is badly oriented or if the ponds are not deep enough.
The selection of the aeration system needs to be done following the type of facilities being used (earth ponds, concrete pond, size of the facilities etc.) and the rearing conditions applied (density, fish size, etc.)
These different types of aerator are available in different motor powers, for scaling to the size of ponds and/or stocking densities to be used.
In a hyper-intensive system, the relationship between the kilowatts consumed and the feed distributed has been followed: this corresponds to approximately 1 kW consumed per Kg of food distributed.
Another oxygenation system is the "super-saturation oxygen" system, which is mainly used in [[trout] farming. This system super-saturates the water in oxygen and therefore allows even higher rearing densities while easing the digestion for the fish. In tropical aquaculture, it is premature to envisage this type of installation due to expense.
Fish graders[edit | edit source]
Fish graders are used to grade and separate fish according to their individual size. This operation is very important because it allows a dramatic improvement in growth performance and improves the overall management of the use of the farm's facilities. If the fish are not graded properly, the smallest ones have difficulty in gaining access to the food (due to physical competition with larger fish) and are stressed, resulting in poor growth performance. Since the size of fish pellets is uniform, the fish size must also be uniform. There are two main types of fish grading equipment:
- Manual fish graders: They are made of boxes that are fitted with differently sized screens, each relating to a range of physical fish size. It is a very simple system that allows small fish to go through the screen while retaining the larger ones in the box. An advantage of the system is that it does not require any electric energy. However, it generates more stress than an automatic grader that is due to heavier handling of the fish.
- Mechanical graders are more sophisticated. Without going into details, it is a machine that is able to grade fish into 3, 4 or 5 different size batches. The system is made of 2 mobile bands or rollers, fixed opposite each other with, a gap between that becomes progressively wider. Fish are conveyed between the bands, being constantly sprayed with water, and they then fall through the gap when the width (corresponding to their size) allows it, smaller fish falling through first. Fish are then transferred to the different tanks through plastic pipes by gravity. The main advantage of this system is that the job is done quickly and without excessive damage to the fish. In intensive fish farming, this type of equipment is very interesting to use, especially when temperatures are high and the fish must be handled with care.
As complementary equipment to the fish grader, fish counters can also be used, often called "bioscanners"; it consists of an electronic register/counter that is placed at the end of an outlet of the fish grader. Using this equipment, the exact number of fish is known after the grading.
Fish pumps & fish elevators[edit | edit source]
This equipment is used to move fish out of the growing units for grading, for loading on a truck or simply for harvest.
Fish pumps function on the same principles as water pumps; they suck fish and water together and pump them out afterwards. All of the movement is done through (flexible) pipe-work. This system is particularly well adapted to floating cage culture.
Fish elevators are based on the concept of the Archimedes screw. This system lifts the water and the fish together.
These two systems are adaptable to a large variety offish sizes (from few grams to more than 5 kg) and species. When high production levels are envisaged, this equipment is very useful indeed almost essential. The ratings for this type of machinery can reach 10 tonnes of fish per hour for the biggest ones.
Feeding[edit | edit source]
There are numerous feeding systems. As discussed in the chapter on nutrition, tilapia is a fish that must be fed often with small quantities. Demand feeders are then particularly well adapted to this fish.
Sketch of a demand feeder.
For smaller fish, clockwork-driven belt feeders are often used. This is basically a container equipped with a belt that is rolled by clockwork action on an axis. [It is also possible to fit such feeders with small electric motors.] Feed is placed on the belt that is going to roll up progressively during 10 hours (clock system) on its axis, releasing the feed slowly. It is a system that is particularly well adapted to small fish. These feeders can distribute 5 to 10 kg of food per day.
Other systems are electrical and distribute feeds periodically according to a pre-defined feeding programme. Feed is distributed within the rearing facilities, usually by mechanical or air-compressed spreading in order to a good distribution over the pond/tank/cage surface. Sometimes, these systems can be equipped with solar power units.
The latest feeding systems used in Europe are highly automated and allow, through a distribution network installed throughout the fish farm, the supply of food to the fish without any handling. The feeds are stored in silos and the weighing of food rations, the feeding frequency and general feeding rates are calculated by computer and are automatic.
Obviously, there are many different systems that cannot all be described in this short paper.
If manual feeding is to be done (which is often the case under the tropics), one tries to train the fish to adjust their behaviour to regular, frequent feedings in specific areas, this being done so as to limit feed wastage. Daily feeding rates must be reconsidered and calculate every week, following t the parameters described earlier (average weight, water temperatures, water quality, etc.). Workers charged with feeding have to pay close attention to fish behaviour (appetite, aggressiveness) and, with experience, a lot of information on the state of the stocks can be obtained during the daily feeding operations.
Transport of live fish[edit | edit source]
During the complete period that is required to take fry up to market size, the fish will be physically transferred several times (from pond to pond, pond to cage etc.) and it is important to foresee the acquisition of all the equipment necessary for these movements.
For short distances and for limited quantities of small fish, such transfers can be done in plastic drums or barrels without using aeration.
When large quantities of fish have to be transferred, it is necessary to use special transport tanks (usually made from fibreglass) that are equipped with an oxygenation system. These tanks can have different volumes, from 0,3 to 2,5 m3, and must be equipped with oxygen (gas) bottles [tanks], and appropriate diffusers (micro perforated pipe, air stones etc.) that are placed in the tanks. The principle is to have an excellent dissolution and distribution of oxygen within the transport tank and, given the correct preparation of the fish and the use of adequate stocking densities, live fish can be transported for long periods of time and over considerable distances.
The transport tanks are either fixed permanently on a trailer or will be handled and moved using a forklift tractor.
Long distance transport requires a separate and complete study and the details of this will not be discussed here.
Complementary equipment[edit | edit source]
Amongst: the general equipment required by a fish farm, the oxygen-measuring meter is one of the more important. A daily check on temperature and oxygen is essential and is an integral part of a fish farm's management. It is recommended to choose a reliable machine of high quality, even if its cost seems high. Electronic oxygen monitors give both temperature and dissolved oxygen measurements that can be expressed as p.p.m.11 (mg/1) and as a percentage of saturation, taking into account the atmospheric pressure.
It is not necessary to make an exhaustive inventory of all the equipment required which are mainly scoop nets, buckets, drums, scales, sets of tools, etc. but good maintenance and repair facilities are needed. Basic laboratory equipment is also useful, including a microscope, a water analysis set, dissecting materials (for disease analysis) etc. parts per million
Equipment suppliers recommended[edit | edit source]
- FAIVRE SARL
7, me de l'Industrie,
FRANCE. Tel: (33) 81 84 01 32 - Fax: (33) 81 84 16 15
- A wide range of professional fish fanning equipment.
42, avenue du Panorama,
B- 6001 Charleroi
Tel & fax: 71 432554
- Range of fish farming equipment. Specialised in aeration.
- S.C.I.M S.A. (Ph. Veyrière)
25 rue Aubert
FRANCE. Tel: 33 04 50 00 - fax: 33 04 82 33
- Modular system of floating cages.
c/ Severo Ochoa, 25,
Poligano de La Grela,
15008 La Coruna
SPAIN. Tel: + 34 81 27 1001 - fax: 34 81 270823.
- Range of fish farming equipment, including floating cages.
- MILANESE SNC
Zona Artigianale, 4
33032 Bertiolo (Udine)
ITALY. +39 432 91 72 24 - fax: 39 432 91 70 34.
- Range of fish farming equipment and fish processing equipment.
- DUNLOP AQUACULTURE
Moody Lane, Pyewipe,
Grimbsby, DN31 2SP
ENGLAND. + 44 1472 35 92 81 - fax: 44 1472 36 29 48.
- Floating cages with a specialisation for exposed sites.
- NCC SUPPLIES Ltd
Cheshire CW10 9NT
ENGLAND. Tel. 44 1606 836 811 - fax: 44 1606 836 088.
- Specialised in air and oxygen diffusion equipment.
- FISHTECHNICK Dr Gerhard Müller GmbH
GERMANY. Tel: +49 55 55 1022 - fax: +49 55 55 384.
- Fish farming equipment, floating cages and fish processing equipment.
- VIKING GLOBAL A/S
NORWAY. Tel: + 47 55 29 28 30 - fax: 47 55 29 20 55.
- Floating cages.
- FARMOCEAN International AB
- Floating cages.
- DRYDEN AQUACULTURE Ltd
Edinburgh EH19 3JQ
ENGLAND. Tel: 44 187 58 22222 - fax: 44 187 58 22229.
- Fish farming equipment. Specialised in water treatment and recirculating systems.
Bibliography[edit | edit source]
AQUACULTURE. of G. Barnabé (1990)
A major publication in two volumes presenting all aspects of numerous species farmed worldwide. It constitutes a reference book, edited by a well-known specialist, Professor Gilles Barnabé from the University of Montpellier. Available in French and English.
INTRODUCTION TO AQUACULTURE. of M. Landau. (1991)
Considered as a best seller in that field, this general work is very useful for any person concerned by aquaculture.
THE BIOLOGY AND CULTURE OF TILAPIAS. of R. Pullin & R. Lowe-McConnell. (1982)
Classic work on tilapia farming. Very useful for a good comprehension of this type of fish.
CAGE AQUACULTURE, of M. Beveridge. Fishing News Books. (1987)
It is almost the only work dedicated exclusively to cage aquaculture. This is "the" reference book on cage aquaculture.
NB.: An important bibliographical list is proposed by: ARGENT Chemical Laboratories, 8702, 152nd Avenue N.E. Redmond, Washington U.S.A. Tel.: 206-885-3777 Fax: 206-885-2112
This list (with order forms) is available free of charge on request at the above mentioned address.
TECHNOLOGIE DE L'ÉLEVAGE INTENSIF DU TILAPIA. of Ch. Mélard, Ch. Ducarme. J. Lasserre. Edit. CERER Pisciculture/Piscimeuse S.A. 8b. Chemin de la Justice. 4500 Tihange.
This booklet summarises several years of research and practical experience from both a research centre and a commercial farm. It tackles all aspects of intensive tilapia farming; breeding, growth, nutrition, pathology and economical aspects bound to this type of fish farming.
LA REPRODUCTION DU TILAPIA. of P Kestemont & Micha. FAO Editions.
This FAO publication compiles a lot of breeding methods of different tilapia species throughout the world. Tilapia biology is described as well as all the problems encountered in this activity.