Page 1 : Cage and Pen Culeus, , 44, , , , y parts of the world, the only water, wie is lowing water or large bodies of water, sh culture is impracticable and it is also, wsible to divert this water into pond, In, valers, therefore, fishes are cultured in small, , vanps where there is water not being used, ther purpose. |, , Simtfic cage culture of fish is @ recent, ‘ developed in many parts of the world, e the culture of fish in cages and pens, ‘tn practiced since long in certain parts of, , JThe present scientific practice Of C88", ng of fish, , like other, , , , ‘riginated from temporary. stock, , ‘ln (9), nainers. culture,, , ‘age, rearing fishes may., ;, enSIMes semi-intensive,, ce feeding (these terms have been, "the end of this chapter): |, ‘ulture was first a in Cambodia, ie as Campuchia) from where such, ited to Thialand, then t© indonet, , *, i, h Wi, “hh 4S transferred to Vietnam,, , |, , 964, ¢, , » Unt 4, cage culture spread WIS“, ly ’, , h, , th, of the world:, May. Since 1980, detail, , on —, the Standardization i ca, , Cage culture can also be practiced in areas i, , be conveniently, or intensive —, eet, , Swe !, , a 0 Osean, ae, nduction, , techniques of cage culture of carps, murrels, and, tilapia from fry/fingerlings to marketable size.), , ‘Countries and the Important Fishes, Used for Culture in Cages, , Fish species traditionally cultured in cages were, chiefly local species. However, the choice of the, species cultured, depends upon the seed availability, and market demand. Presently, among inland fish, species, Salman (Oncorhynchus), trout (Salmo),, , fh (Ictalurus punctatus), milk fish, ae eee | big carp (Aristichthys :, , , , , , , , , , , , , , Salmo gairdneri, — Common carp, Barbus, Channa SPP! and Anabas, testudineus, oo, 5, Us Sanus, alles ad ON 6,199 eons, s * of cuttle, the culture of, cages) ‘anos, Tilapia wnt Cae °, i Heteropneustes,, | , Sardinella, used in

Page 2 : ww), , nobilis) and common curps are the most common, species and many more species such as murrel,, tilapia, magur, singhi, etc., are also now taken in, cage culture in different parts of the world., Among marine fish species, sea bass, and sea, bream are the most common., , ~_Shape of Cages, [The cages of various shapes such as square,, , rectangular, circular or boat shaped are used in, many countries, although use of square and, , Tectangular shapes are more common., _/Size of Cages, , [The size of cages vary greatly from 40 - 10000, m°. The largest size of cages are about 10000 m°., But the practical sizes of cages adopted are, usually 20 - 60 m’. | Even 40 m_ wide, circumference cage is used for culture of seabream, and sea bass in Spain. [Smatiest cages of, , measuring about 1 m° are often used for rearing, fry to fingerlings or early juvenile stages. "), , ~/Types of Cages, Cages are chiefly of the following types :, (1) Floating cages,, (2) Fixed cages,, , float, , , , Fig. 1. Typical unit of floating cage (a line diagram), , Floating cmpe, , , , frame, material, , ‘weight, , Cage and Pen Culture, , (3) Submerged cages,, (4) Movable cages., , Generally floating-type end movable of Cages, are used (Fig. 1), however, fixed and submerged, and fixed cages are also in Practice] Eloating type, cages consist of a floating unit in the form ofa, framework and a flexible mesh net Cage-bag, suspended under it](The floating unit may consi, of styrofoam polythene pipes, empty barrels etc,, The buoy units are often built into framework, impregnated with bamboo , spars or wood or, welded aluminium bars. Nylon is normally used, for the net, however, weld-mesh or woven split, bamboo may also be used. Cages of under water, net volume of 200 and 500 m> are the ‘most, suitable and preferred ones] It is a general practice, to have double netting, the outer one Serving as, predator net to protect the inner one where the, fish stock is maintained. Commonly used cage in, Norway has eight-sided floating framework of, timber,, , vy Mal, Cra, , ve, Whe, , ui f, , , , , , Fig. 2. Floatin f jetty along the shor, 1B Cages series moored to a jett), —_ 2 mee

Page 3 : [441, , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ‘— [, s Ty, 2 = concrete, I block, A, chain, wire rope, te, H, tk A :, = mun n q, ed, lit, er f, L, 3_ A series of ‘oating’ cages, moored together A. Seen from above and B. Side view (a line di, . iew (a line diagram)., , , , , , (rrangement of cages/“There are several, fish farm (Fig. 2, Ic is preferable to moor cages to a jetty, il easy approach, in order to facilitate work and, , f arranging the cages in, , ninimise labour Costs., , [nstallation of different cages, , Suilable site fulfilling the environmental and water, quality requirements of cultured species to be, tuken under cage culture has to be selected. The, methods adopted for installation of cages (Fig. 1), depends on its position in the system. If floating, cages are proposed to be installed, then these have, to be installed in lakes/reservoirs. Fixed cages are, installed in rivers, streams or fast flowing waters., Similarly, submerged cages and movable cages can, be installed in offshore region of the sea as, practiced in Japan., , Suitable sites for cage rae, , Properly sheltered sites with sufficient water flow, , i mi or, to effect adequate _mwvxan and aeration ar, sites for cage ‘arms. |, , recommended __ suitable iy, industrial sites are” genera, , Contaminated and, , avoided. In cold climates, areas that receive pale, fetaicsterceffucnis ‘maygbe pete e, ‘ “temperatures generally accelerate 2m 5, ve growth and ultimately productivity ©, , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Fig, 4, Cage culture., , fishes. The floating cages must be installed on the, sides of a central walk way to facilitate, day-to-day work on the farm. Many of the cages, designed for use in protected areas, , A, , Principal aim of cage cure Vf Memecal tet, , [The principal aim of the fish culture in the cage is, , to practice monoculture of selected_s cies. Cage, has a promising, , culture of murrels in swamps, in some, , future. Cage culture has been used, countries in very fertile waters (polluted from, , sewage) with very good results. |, , at present, are, like bays, fjords and lake:

Page 4 : Designing of cages, , {ie includes materials used for cage fabrication,, types of cages and their installation procedure in, the aquatic system. Materials used for fabrication, of cages varies in relation to the body of the cage,, frame, floats, sinkers and attachment of feeding, , equipment in the cage. The body of the cage is, made of nylon cloth (8 mesh/mm) knotless or, knotted webbing depending on the size of fish to, be reared." Frame of cage may be collapsible,, made of galvanised iron, conduit iron tube or high, density polypropylene ~ (HDPP) — _ pipes. _ [Other, common plastic polymer products used for cage, designing are mainly low density polypropylene, (LDPP), polypropylene (PP), polyvinyl chloride, (PVC), Polystyrene, polymide, polyethylene,, fiberglass reinforced plastic, et¢)/In many cases, wooden or bamboo frames are used for cages,, although the durability of these is less in, comparison to that of frames fabricated out of, plastic polymers or irons. |, , materials for floats used in cages are, either plastic, wooden or other cheap materials, available. Sinkers made of clay, concrete, bricks or, Stones are used in keeping the Position of cage., Auto feeder or demanding feeders are installed in, cages. In Spain and Austria, solar Powered feeders, are installed in cages”|, , jm species, <, , [There are about SO species of fresh and marine, water fishes cultured in cages. However, there are, well known six families of freshwater fishes such, aS Cyprinidae, pangassidae, claridae, ictaly, idae,, channidae and cichlidae, cultured in cageijUnde,, brackish and marine fishes, the fish species, belonging to —_salmonidae, Carangidae and, mugillidae are most common.), , In India. cal fishes viz, Mystus Spp., Clarias, batrachus, Heteropneustes Sossilis,, (Channa spp.), climbing Perch (Anabas), ¢ s, etc., are responding well to cage culture p; wer, Cage culture in India has been starteq in, Bihar and Karnataka states,, , , , , , Assam,, , ractices,\, , Cage and Pen Culture, , J/Stocking density, ‘ages are stocked with 38-63 mm (15.25, inches) fishes of the desired species during August, to October. Some cage owners, however, prefer io, stock fingerlings or even early juveniles. Fry of, desired species are obtained from natural sources, such as rivers, canals and paddy fields with weirs,, , traps, seines and dipnets., , (There is no standard stocking density of fish, in cage culture. This is because of various species,, cage size, mode of installation, water environment, and management. However, the range of stocking, density varies from 75-300 fry/m? of water in, some Asiatic countries} / However, in India, the, stocking density of carp fry is about 210, individuals/ m? and for table size fish Tearing, the, desity of carp fingerlings varies from 28 - 49/m2,, , (For Tilapia cage culture, the stocking density, “ranges from 100-200 fingerlings/m2,]/For murrel, cage culture, the stocking density adopted is 40, fingerlings/m2.\ Variations in stocking density has, been reported. However, Japanese believe that fish, stocking at initial Stage should occupy 45% of, cage volume so that fish can have normal growth., , Stocking proportions, As adopted in China, the artificial food, fishes Occupy 85%-90%, , and natural food eaters, culture-\, , Feed, , eating, of total stocking density, oecupy 10-15% in cage, , [Feea used in the cage culture depends on the, Species t0 be cultured. After 8-10 days of, acclimatisation in the floating cages, fishes are, , Biven artificial feed, The common feed, , the cage, is the mixture wh ah, and soyabean cake, With this feed the {, Fate obtained has been reported to be 1.8.), Fish Production, , ‘py this Practice, Chinese have proved, , = 75kg/m*/year is Produced in A, 20 metre depth and over 5.0 mg DO., , , , ead

Page 5 : pen Culture, , , , , , , , , , , , , , , , , , , , F hallow lakes and hi, pile in S Channels,, is much lower (Lisifa, 1999 oe, , In India,, Py a, , lof cage arca in 243 days of Tearing in the, ripathi, 1990)5 It is revealed that, each, re diameter polarcricket cage with Sm, , has an output of ten tonnes of bass and, every two years in Spain. In Spain, 50-60, of sea bream in 4 cages of 1600 m3 et, recorded to be produced in 1991 (Fish, g International, 1991 Vol. 18, No, 6)., , general, production usually Tanges from, 25000 ke/large cage/year depending upon, factors, specially the quality and quantity, administered., , ing period, , , , cage culture, harvesting usually takes place, , March to August after the culture Period, from 9- 11.5 months depending upon the, , cultured.”, , ics, , culture of fish is generally considered to be, lucrative practice. For this reason, number, es operated, has been increasing very rapidly, nt years. Annual income from cage varies, US $ 2500-31500. In Vietnam,, ximately more than 10,000 cages are in, ice of various sizes. Fish cultured in cages,, imes may be affected by pathogens and, ites, causing decline in production. |, , n oa Fish Culture in Cages, , , presented his research paper in a, rence on "Advances in Aquaculture” held at, , Japan (26 May-2 June 1976) sponsored by, , entitled “A review of cage culture and its, i and has _ reported, ages of cage culture., , ) Possibility of making maximum use of all., , available water resources., , Economic use of water., ) Reduces pressure on land resources., , [443, , Cage culture facilitates, Several type:, bod, , Y. f, Easiness in the daily observation of the fish, Population,, Easiness in the control of fish reproduction, (Specially in Tilapia species),, Easiness in the control of competitors and, Predators,, Reduction in the fish handling., Reduction in the fish mortality., Easiness in control of parasites., Control of the diseases becomes manageable,, Specially in floating cages., Fish harvesting is easy and flexible., Complete harvesting of the fish production., Harvesting of Telatively uniform product., Initial investment is relatively small., Storage and transport of live fishes is greatly, , facilitated:, , combinations of, S of culture with in one water, , (3), (6), M, , (8), (9), (10), (1), , (12), (13), (14), (15), (16), , Vficedtantages of Fish Culture in Cage, , (1) __ Since,, , cages occupy space, hence make, navigation difficult i, , (2) Reduce the land value of the sit® and also, alter the current’ flow and_ increase, sedimentation rate., , (3) Cages may alter the distribution of flora and, fauna and consequently the behaviour of, local fishes., , (4) Cages in freshwaters- may over-graze the, algal populations and, therefore, primary, , productivity diminishes., , Release of unconsumed food and faeces of, the cages may adversely affect the water, quantity., , (3), , following « Lirhttation of Fish Culture in Cages, , (1) Difficult to apply when the water surface is, very rough., , (2) Need for adequate renewal of water in the, cages for elimination of metabolites.