fish hatcheries and its types, different types of hatcheries

hatcheries; fish

1. Introduction
Need for hatchery
Role of hatchery
The various essential components of a hatchery
Traditional hatcheries
Modern hatcheries
Planning of hatcheries construction site selection
Essential components of hatchery complex
Conclusion
Reference
SYNOPSIS

2. INTRODUCTION
Ahatcheryisthemostvitalcomponentinmodern
carpfarming.Hatcheriesarenaturalorartificial
confinementsusedforbreedingandhatchingthe
eggs.Someauthorsconsiderthetermhatcheryinits
enlargedsenseasafacilityrightfromfishspawning
toproducingfishfingerlingsforstockingingrow
outponds,fishfatteningandrearingofbroodstock.
Buthatcheryisindoorfacilityforfishspawning,egg
incubation,hatchingandrearingthehatchingsto
spawnstage.

3. Inearlierdaysavailabilityoffishseedwasentirelydependentonwild
catchfromriversandlargereservoirsduringrainyseason,whichwas
accomplishedbyseveralproblemsandinpresenttime
Quantityofseediscollectedfromthereveriessourceisverylow.
Fishfarmerhadtodependonlyonnaturalwaterbodiesfortheir
seedrequirements.
Seedtheycollectedconstitutedmixedvarietyofdifferentspecies.
Duetolakeofknowledgetheyrearedmixedvarietywhichresultedin
lesssurvivalrate.
Duringthetransportationofseedthereoccurredhighmortalityof
seed
Thusforthesereasons,hatcheryconstructionissonecessaryto
overcomesuchproblemsandtoobtainmaxquantityofseedinproper
condition.
NEED FOR HATCHERY

4. ROLE OF HATCHERY
Theroleofhatcheryisvitalandithasinfectaugmentedtheproductionoffishseedand
createdenvironmenttoenabletoproduceanyqualityandquantityofseed.Statefederal
hatcheriesareexpectedtobecomeincreasinglyimportantastoolstopreserve
biodiversitybymaintainingrare,threadedandendangeredgenotypes.
ESSENTIAL COMPONENTS OF A HATCHERY
Broodfishpondtoholdadultfishforspawningdonorsofpituitaryglandandto
accommodatespentmaleandfemalefishes.
Nurserypondsforrearinglarvaetofrystage.
Rearingpondsforgrowingfrytofingerlings.
Pondsforproductionoffishtosupplybroodfishpondsanddonorsofpituitary
glands.

5. TRADITIONAL HATCHERY
EarthenHatchingPits
Theearliestdeviceforhatchingcarpeggswastheearthenhatchingpitsemployedbythecrapbreeders.There
arespeciallydesignedpitof3*2*1dimension.Pitsareduginseveralrowsandtheinnerwallsareplastered
withmudi.e.redsoil.Thefertilizedeggscollectedfrombundtypesoftanksareputintothehatchingpits.
Approximately36000to400000eggsperpitarekeptandhatchingtakesplaceinabout24hours.Aconstant
flowofwaterismaintainedtoensureproperaerationandtoreducetheaccumulationofwastes.Afterabout3
days,whentheyolksacistheabsorbedtheavailablespawniscollectedwithapieceofclothandistransferred
tonurseries.
Earthen Pot Hatchery
Thisisoneoftheearliermethodadoptedforbetterhatchingrates.Thefertilizedeggsarecollectedfromthe
bundandarekeptinanumberoflocallymadeearthenpotsarrangedinaparticularway,andthisfurnishesa
flowingcurrentofwater,cooledbysurfaceevaporationoftheporousearthenpotswhichthecrapeggs
hatched.InthismethodtosomeextentthefluctuationsoftemperatureandpHaremoderatedbakedclay,
vesselsthoughcheap,easilyreplaceableandporoushavethedisadvantageofbeingopaque.

6. EarthenHatchingPits
Earthen Pot Hatchery

7. •DoubleClothhatchingHapa
Itwasstatedin1976,inthismethodtherearetworectangularhapas,calledouterhapaandinner
hapa.Theouterhapahasasizeof2m*1m*1mandtheinnerhapaofsize1.75m*0.75m*0.5m.the
outerhapaismadeofclosemeshedcottoncloth(4060/mch)andtheinnerhapaismadeofround
meshmosquitonettingcloth.Thedepthofwatermaintainedintheinnerhapaisaround30cm.the
numberofgeesputforhatchingnormallyis75000to100000thehatchingmovesthroughthemesh
intotheouterhapaandafterthattheinnerhatchinghapaisremovedalongwitheggsshellsandthe
spoiledeggs.Thehatchingintheouterhapaarekeptforaperiodof48hour(2to3days)tilltheyolk
sacisabsorbed.
•FloatingHapa
Floatinghapamethodistheimprovedone,inthishapaismountedontheframeswhicharemadeby
joiningpolytheneoraluminiumpipes.Floatsareaddedtofacilitatefloating.

8. DoubleClothhatchingHapa
FloatingHapa

9. VERTICAL HATCHERY
GLASS JAR HATCHERIES
istheIndia’sfirsteverhatcheryinwhichthedevelopingeggscanbewatchedintransparentateyelevel.It
hasabreedingtank,incubationandhatcheryunitandspawnery.Afreshwaterpondorborewellisused
asawatersource.Overheadtankswith5500litterscapacityinallareplacedconnectedtohatchery.This
unitconsistofabatteryofcylindricalshapedglassjarwithconicalbottomhaving6.35littercapacity.
About50000eggsarehatchedinasinglejar.
PLASTIC BUCKET HATCHERY
Plastichatcheryismadeoftwoparts.Oneistheouterplasticbucketwithperforatedaluminiumbinegg
vesselandotherpartisgalvanizedironsheetspawnery.Theplasticbuckethaving3outletsatthetop,
theheightis47cmandthediameteris30cm.waterholdingcapacityis45litters.
MODERN HATCHERY

10. GLASS JAR HATCHERIES
PLASTIC BUCKET HATCHERY

11. CIRCULAR HATCHERY
Modern carp hatchery CIEF D-80 model
IntheyearmoderncraphatcheryCIEFD-80modelwasdesigned.Thismoderncraphatcheryisnamed
afterthenameofEx.DirectorofCIEF,Dr.S.K.Dwivedi.Inthismodeltheeffortshavebeenmadeto
controltheenvironmentparametersliketemperature,oxygen,silt,waterflowandspaceformovement
ofeggs.Thehatcheryconsistofoverheadtankasasourceofwatersupply,coolingtower,hatchery
section,compressorforaeration,verticalhatcheryjar,PVCpipes,valves,showers,channels,hatchery
standsandhapas.Thistypeofhatcheryhastwopartsoneisincubationtankandtheotherisegg
collectiontank.Heisaverticaljarcomplexoffourunits,havesixfunnels.Thetotalcapacityofthe
hatcherycompleteis50lakheggsatatime.
ModernCarpHatcheryCIFED-81Model
Thiswasthedevelopedin1981atCIEF.ItisanimprovedversionofcraphatcheryModelD-80andthe
entiresystemworksontheprincipleofD-80.ThismodelD-81consistofbreedingandhatchingunits
withimprovedwatersprayarrangementsandensuringmoreeffectiveaeration.

12. CIRCULAR HATCHERY

13. Operation
Beforeloadingofeggswaterisfilledinjarsfromoverheadtank.Theflowofwaterisregulated2-3lit
/jars/min.Eggsarecontainersareplacedinthejarandtheaerationisarranged.Eggsareloadedas
percapacity.Oncehatchingcompletedflowofwaterisincreasedforspeedytransferofhatchings
aretransferredinspawnery,theoverflowingfromjarisstopped.Sprayandaerationinspawneryis
keptunderoperationtillyolksacisabsorbed.
Modern Carp Hatchery CIFE D-82 to 85 model
ThisisacommercialsystemandworksontheprincipleofD-81.Themainpartsofhatcheryareover
headtank,jars,pipelineseggcontainersspawncollectiontankandaerationsystem.Themodelsare
D-82toD-85andthehatcheryisoperatedinthesamewayasincaseofCIFED-81model.

14. CHINESE HATCHERY
Themoderneco-hatcheryorChinesehatcherycomprisesofthe
followingcomponents:
Overheadtank.
Spawningpool.
Eggcollectionchamber.
Incubationandhatchingchamber.
Spawncollectingchamber.

15. CHINESE HATCHERY

16. CONCLUSION
Quantityofseediscollectedfromthereveriessourceisverylow
.
Fishfarmerhadtodependonlyonnaturalwaterbodiesfortheir
seedrequirements.
Seedtheycollectedconstitutedmixedvarietyofdifferent
species.
Duetolakeofknowledgetheyrearedmixedvarietywhich
resultedinlesssurvivalrate.
Duringthetransportationofseedthereoccurredhighmortality
ofseed
Thusforthesereasons,hatcheryconstructionissonecessaryto
overcomesuchproblemsandtoobtainmaxquantityofseedin
propercondition.

18. FISH TRANSPORTATION
DRUGS
The drugs used in transport medium, aimed at
increasing the capacity volume of the transport units
and preventing physiological and health damage to
the fish, constitute an integral part of the complex
problem of fish transport.
They include the use of anaesthetics, water
hardening and oxygen-producing chemicals,
bacteriostatics, buffering and antifoam chemicals.

19. USE OF FISH TRANQUILIZERS
⚫During transport, sedation of the fish is desirable, since
oxygen consumption and CO2 and NH3 production are
all decreased. However, deep sedation is undesirable
because the fish may fall to the bottom, pile up and
smother.
⚫If pumps are used, the fish may be pulled into the
screen, the air may move the deeply sedated fish about
and cause a loss of scales.
⚫It is best to sedate the fish in the holding facility for 30
min before loading and then to continue exposure to a
lower concentration of sedative during transport.

20. ⚫The use of anaesthetics should not be relied on for increased
load carrying capacity. Other methods are safer and
dependable.
⚫The use of anaesthetics on food fish that will be consumed
soon after exposure is not legal. Consideration should always
be given to the legal status of a chemical and possible
consequences to the consumer.
⚫Anaesthesiausually applies only to transported brood fish.
⚫In practice, the fish are first tranquilized with the normal dose
and put into the transport tank, where original concentration is
diluted by 50 percent by adding the same amount of fresh
water. The brood fish will remain tranquillized well in that
diluted solution.

21. ⚫MS-222 is a very mild tranquilizer and fish easily recover
from its effects even after a long stupor.
⚫MS-222 to water at the rate of 20 mg/l for carp and
grass carp, 10 mg/l for silver carp, and 35 mg/l for
bighead carp or sheatfish. At these concentrations the
fish can still hold their natural position but their
respiration and motility are significantly decreased.
⚫When applying this anaesthetic, the mass of transported
fish in a unit volume can be increased by 50–150
percent, but it is best to test it before application.

22. ⚫Quinaldine (2–4 methylchinolin) is a toxic liquid and must,
therefore, be handled with care. The fish are usually treated
with it when they are held in a large volume of water, such as
a large tank.
⚫Apart from these two tranquilizers, other drugs are to be
used. Phenoxyethanolis another chemical that has recently
come into use as a fish tranquilizer. It is milder and less
effective than MS-222, but it is far cheaper; 30–40 cm3 of
phenoxy-ethanol are mixed with 100 litresof water for the
treatment.

23. APPLICATION OF SODIUM CHLORIDE
AND CALCIUM CHLORIDE
⚫Handling stress and delayed mortality of fish can be
decreased by the addition of sodium cloride(NaCl) and
calcium chloride (CaCl2) to the transport water.
⚫The sodium ion tends to “harden” the fish and reduce slime
formation, and the calcium ion suppresses osmoregulatory
and metabolic disfunction.
⚫Calcium chloride may not be needed in hard water already
containing high concentrations of calcium.
⚫Recommended the addition of 0.1 to 0.3 percent salt and 50
mg/l calcium chloride.

24. ⚫Some of the fishes that tolerate wide ranges of salt in the
water, such as striped bass, tilapias, carp, can benefit from
as much as 0.5 percent salt.
⚫Addition of 0.2 percent salt is recommended also by
Johnson (1979).

25. DRUGS AS OXYGEN SOURCES
⚫Use of hydrogen peroxide on transported carp fry and
found that one drop (1 ml = 20 drops) of hydrogen
peroxide (6 percent concentration), applied to 1 litreof
water, increased the oxygen content by 1.5 mg/l when
the temperature was 24°C. CO2 content and water pH
were not influenced by the addition of hydrogen
peroxide.
⚫Dissolved oxygen was measured by the Winkler
method.

26. BACTERIOSTATIC
CHEMICALS
⚫Antibacterials are also used to check the
development of bacteria in transport units.
⚫Antibacterials may strengthen the resistance of
fish, but they are probably of little value as
bacterial checks in transport tanks.
⚫Rare exception would be in the case where a
superficial infection of an antibacterial-
susceptible bacterium was in progress.

27. BUFFERS
⚫Among other chemical additives, buffers such as “tris-
buffer” (tris-hydroxylmethyl-amino methane) are helpful in
controlling pH at a favourable value of 7 to 8.
⚫The accumulation of carbon dioxide in bag transport
allows for a decrease in pH, because carbon dioxide is an
acid.

28. AMMONIA CONTROL
⚫To control ammonia concentration in the transport bags
when the transport is expected to be long, it is
recommended to use clinoptilolite, a zeolite mineral.
⚫The doses of 10–40 g/l ; the concentration of non-
ionized ammonia nitrogen never exceeded 0.017 mg/l
in bags containing even the lowest dose of clinoptilolite,
whereas concentrations as high as 0.074 mg/l were
recorded in the control bags left without clinoptilolite.

29. Drug Name Dose
MS-222
20 mg/l for carp, grass carp<br>10 mg/l for silver
carp<br>35 mg/l for bighead carp or sheatfish
Phenoxyethanol
30–40 cm³ of phenoxyethanol mixed with 100 liters of
water for treatment
Sodium Chloride and Calcium Chloride 0.1 to 0.3 percent salt<br>50 mg/l calcium chloride
Hydrogen Peroxide 1.5 mg/l
Ammonia 10–40 g/l

30. VARIOUS DRUGS USED IN TRANSPORTATION
Fish Drug Common Name Typical Dose
Tranquilizers Tricaine methanesulfonate (MS-222) 50-100 mg/L
Antibiotics Erythromycin 10-50 mg/L
Tetracycline 5-10 mg/L
Enrofloxacin 2-5 mg/L
Antiparasitics Formalin 10-100 mg/L
Praziquantel 2-5 mg/L
Copper sulfate 0.1-1 mg/L
Potassium permanganate 1-2 mg/L
Anesthetics Benzocaine 10-20 mg/L
Lidocaine 5-10 mg/L
Propoxur 5-10 mg/L

31. DRUGS USED IN BREEDING
FINFISH & SHELLFISH

32. FISH BREEDING
To control In fish breeding, drugs are
sometimes used to induce spawning and
enhance reproductive success.
The use of drugs to enhance spawning and
reproductive success in fish breeding should be
done under the guidance of experts and in
accordance with applicable regulations. Here is
a general overview of how drugs can be used
to enhance spawning and reproductive
success:

33. In fish breeding, drugs are sometimes used to induce
spawning and enhance reproductive success. Here are a few
drugs commonly used in fish breeding:
Hormones
Hormones are often used to induce spawning in fish species
that do not naturally reproduce in captivity or to synchronize
the reproductive cycle of fish. Common hormone
preparations include synthetic versions of the naturally
occurring hormones such as gonadotropin-releasing hormone
analogs (GnRHa), luteinizing hormone-releasing hormone
analogs (LHRHa), and human chorionic gonadotropin (hCG)

34. Antibiotics
Antibiotics are used in fish farming to prevent and treat
bacterial infections. They are administered to fish through
medicated feed or by adding them to the water. Examples of
commonly used antibiotics include oxytetracycline, florfenicol,
and erythromycin.
Parasiticides
Parasiticides are drugs used to control and treat parasitic
infections in fish. They can be added to the water or applied
topically. Common parasiticides include formalin, malachite
green, and praziquantel.

35. Anesthetics: Anesthetics are used during fish handling and
surgery to minimize stress and pain. They are used to sedate or
immobilize fish temporarily. Commonly used fish anesthetics
include tricaine methanesulfonate (MS-222) and benzocaine.
It's important to note that the use of drugs in fish breeding
should be carried out under the guidance of a veterinarian or
fisheries professional to ensure proper dosages and minimize
any potential negative impacts on the fish and the environment.

37. VARIOUS DRUGS USED IN
BREEDING
Fish Drug Purpose Recommended Dose
Formalin Parasite control 25-50 mg/L for 1-2 hours
Malachite Green Fungal and external parasite control0.2-0.5 mg/L for 1-2 hours
Methylene Blue Fungal infections, egg fungus 1-3 mg/L for 1-2 hours
Praziquantel Flukes and tapeworms 2 mg/L for 24 hours
Copper Sulfate Parasite control 0.2-0.5 mg/L for 24 hours
Acriflavine Bacterial and fungal infections2-5 mg/L for 1-2 hours
Oxytetracycline Bacterial infections 10-50 mg/L for 5-7 days
Metronidazole
Protozoan and anaerobic bacterial
infections
100-200 mg/L for 5-7 days
Kanamycin Bacterial infections 50-100 mg/L for 5-7 days
Erythromycin Bacterial infections 50-100 mg/L for 5-7 days
Levamisole Internal parasite control 2 mg/L for 24 hours
Dimilin Gill flukes and anchor worms 2 mg/L for 24 hours
Salt External parasite control 1-3 grams/L (depending on species)
Hydrogen Peroxide External parasite control 10-100 mg/L for 5-30 minutes
Formaldehyde/Malachite Green
Combination
Parasite control
10 mg/L formaldehyde + 2 mg/L
malachite green for 1-2 hours

40. Fish brood stock management
and transportation of brood fish

41. Management of broodfish ponds
•Broodfish - prerequisite for all induced breeding programmes
•Good broodstock - better breeding responses, increased fecundity, fertilization,
hatching and larval survival rates and more viable fish seed
Carp broodfish pond:
•Carp broodstock ponds - large (0.2-2.5 ha), 1.5-2.5m deep, rectangular, seasonal
or drainable and earthen in nature
•Water inlet and outlet - simulate riverine/fluviatile conditions
INTRODUCTION

42. Source of broodfish:
•No reliable source
•Hence the source of future brood fish is stock ponds from the same farm or
different farms or live adult of different species procured from capture fishery
waters like rivers, lakes or reservoirs

43. Care of brood fish:
•Recommended stocking density of carp broodfish is 1,000-3,000 kg/ha
•While rohu and mrigal are stocked at a higher rate, catla is stocked at a lower rate
since it requires more space for proper gonadal development
•Stocking rates are manipulated to permit individual and collective care of broodfish,
enabling them to get nutritional and environmental advantages for onset of right
degree of maturity

44. •A gravid fish when held by hand with tail up should practically ooze milt and also
ova
•Carp broodfish fed with a traditional diet consisting of rice bran and oil cake (1:1)
at a feeding rate of 1-2% body weight daily
•In addition to the artificial feed the grass carp is also given tender aquatic
weeds/terrestrial grass.

45. •Common carp demand their separation from other carp species due to their
natural breeding in ponds with aquatic vegetation
•The common carp broodfish is segregated sex-wise and stocked in separate ponds
to prevent accidental spawning in pond
•Catla, in particular, needs to be separated from the rest of the species as it shows
poor response to hormonal injection when stocked with other species
•It is believed that catla broodfish need special care and diet such that deposition of
mesenteric fat in the maturation phase does not hinder gonadal development of
the species.

46. Broodstock management practice in Karnataka State
•Described by Basavaraja et al. (1999)
•The number and quality of eggs produced are significantly affected by the
conditions under which the broodstock is maintained
•The quality of broodstock diet, feeding regime, the quality of broodstock and water
management are the principal factors that influence the condition of the
broodstock
•Most seed farms raise broodstock in their own farm (there are instances of
inbreeding depression, as reported by Eknath and Doyle (1985) and maintain them
in ponds at a density of 1,000-2,500 kg/ha.

47. •The earthen broodstock ponds vary in area from 0.2 to 1.0 ha, with depth ranging
from 1 to 2 m
•The main basic steps in the preparation of broodstock ponds are :
–control of aquatic weeds, which in done manually;
–eradication of unwanted fish by applying mahua oilcake at 2,000-2,500 kg/ha
–pond liming at 100-200 kg/ha depending on the pH of soil and water

48. •Fertilizing the pond with cattle dung, at 15,000-20,000 kg/ha/yr or poultry manure
at 5,000-10,000 kg/ha/yr to enhance heterotrophic food production
•200-400 kg/ha/yr NPK mixture is applied in split doses at fortnightly or monthly
intervals
•The initial dose of organic manure is reduced by half if mahua oil cake is used as
piscicide

49. •After stocking the pond with carps that are one-year-old or more, they are fed with
a conventional feed containing a mixture of groundnut oil cake and rice bran (1:1
or 1:2 ratio) at 1-2% b. w., once daily
•To ensure better and timely development of gonads, fish breeders use a special
broodstock diet (protein : 25-30%) prepared using locally available cheap
ingredients
•This diet is nutritionally superior, advances maturation and spawning by one or
two months and results in increased fecundity and better seed quality.

50. •This diet is given at 2% b.w. daily, starting in December
•At some farms about a third of the broodstock will be injected with a low dose of
HCG at 6-7 mg/kg body weight every 20 days, starting from mid-February for
advancing maturation so as to induce spawning by the end of May
Ingredients %
Rice bran 25
Groundnut oil cake 25
Fish meal 10
Maize 10
Broken rice 10
Horse gram 10
Blackgram 10
Table : Feed ingredients and their contribution to broodstock diet

51. •At some seed farms, a few vitamin E tablets are mixed, in the diet to facilitate
gonad development
•Algal blooms and oxygen depletion -common problems in broodstock ponds
•Overcome by frequent water exchange
•Infestation by Lernaea and Argulus on catla are common - manual removal of adult
specimens, followed by a dip treatment in a mild solution of potassium
permanganate
Lernaea Argulus

52. Transportation of broodfish
•Transport of bigger fingerlings/yearlings and broodfish in small packing containers-
not economically feasible
•Truck mounted open tanks with facilitates for mechanical aeration and/or
circulation were initially used quite successfully (Hora and Pillay, 1962; Mammen,
1962)

53. •Open canvas containers (1m x 1m x 1.25m) are used in Punjab and Madhya
Pradesh for transporting major carp breeders
•In those States galvanized iron drums of 180 l capacity are also used
•In India, two successful models of closed system of live-fish carrier were designed.
One is due to Mammen (1962), which he called `Splashless tank’.

54. •The later model of the splashless tank is of a petrol tanks design of 1,150 l capacity
with an autoclave-type lid
•It has a built-in aeration system for supplying compressed air, which works on a
belt driven by the engine of the transporting vehicle
•An oxygen cylinder is carried only as a stand by for emergency
•The inner surface of the tank is lined with U-foam which prevents physical injury to
live fish during transport
•A total weight of about 250 kg live fish can be transported at a time in the
splashless tank, as also 90,000 carp fingerlings
•The load ratio of fish to water in this type of carrier in about 1 kg of fish per 4.5 l
water

55. Fiberglass transport tank with four compartments, each with an electric aerator (arrow). Additional oxygen is provided through carbon
rods or micropore tubing on the bottom of the tank (Piper et al., 1982)
Installation of transport tanks on a truck. The transport capacity of the truck is about 8 000 litres; when the truck is combined with a trailer,
the volume of the fish tanks is about 15 000 litres

56. •Patro (1968) developed a tank which has an outer chamber of 120 cm diameter
open from top and a slightly smaller one closed from top; the latter, during
transport, fits inside the former
•The top of the inner chamber is provided with an air vent and an oxygen valve
•The outer chamber serves as a storage tank and is initially filled with water along
with fish to be transported

•The inner chamber, which is shipped from the upper open end of the water serves
as an oxygen holding chamber at its top and is lined throughout with U-foam to
prevent fish from sustaining injury during transport
•This double-barrel type carrier as stated by Patro can transport a total weight of
100 kg of live fish at a time

58. Multiple spawning of fish

59. Multiple spawning
•Refers to spawning fish, female in particular, more than once in a season
•This is particularly important in carps as they have narrow captivity breeding
season and are difficult to bring them to maturity to maturity in captivity.
•Resulted in the successful spawning of major carps up to four times in a season

60. Factors that facilitate multiple spawning of carps are :
1. Manipulation of water quality
2. Manipulation of diet
3. Use of ready-to-inject spawning agents
4. Use of circular spawning and hatching tanks

61. Broodstock management
•Spent brooders of the previous season are preferred as initial broodfish for
multiple breeding.
•They are fed with a protein-rich diet, having a protein content of % and fat content
of %.
•Water exchange - 30-40% every month.
•Minimum handling of brooders.
•Disinfection of spent brooders
•Rearing of spent brooders with special care.

62. Schedule of multiple spawning:
First spawning (March-April) - Spawn yield :

Interval 40-45 days

Second spawning (May-June) – spawn yield :

Interval 40-45 days

Monsoon spawning (June-July) – Spawn yield :

Interval 40-45 days

Fourth spawning (August-September) – Spawn yield

63. Advantages of multiple spawning :
1. Increase period of seed availability, i.e. seed will be available over a longer period
2. Number of broodfish (female) to be maintained gets reduced
3. Seed production potential of the farm could be improved.

•Recent studies conducted at CIFA, Bhubaneswar show that rohu could be induced
bred even in the month of January

64. Seed production of
grouperS

65. Distribution and importance:
•Groupers belong to the family Serranidae and Order Perciformes.
•Important species are Epinephelus tauvina and E. malabaricus.
•E. tauvina is found mainly in the east coast of India
•Can be cultured in brackishwater and marine waters.
•They are demersal, highly carnivorous and highly predatory, cannibalistic when
food is scarce.

66. •An important foodfish, commands high price (up to Rs. 400/- per kg)
•Suitable for culture in net cages as well as in ponds.
•Grows to 500- 800 g in 6 months, maximum size recorded is 100 cm.
•Spends the growing phase in shallow brackishwater, estuaries and rivers.

67. Identifying characters:
•Elongate and compressed body, with a deep caudal peduncle.
•Head is pointed with a concave dorsal profile , becoming convex in front of the
dorsal fin.
•Mouth large, slightly oblique and the lower edge of the pre-opercle is serrated,
with a strong spine.
•Adults are greenish or bluish above and silvery below.
•Eyes are bright pink, glowing at night.

68. Food and feeding:
•Highly predatory, feeding on small fish and crustaceans.
•Juveniles are omnivorous.
•Fry feed on zooplankton, while fingerlings prefer small crustaceans, worms,
mollusks, etc.

69. Breeding season:
•Spawning season is November – May.
•It migrates to deeper waters for breeding.
•Is a protogynous hermaphrodite (functions first as female and then turns to male
after spawning, i.e. natural sex-reversal).
•Fish in the weight range 2 – 3.5 kg are females, whereas those in the size range 3.5
– 5.0 kg are males.
•Three to four year-old fish show 1:1 (M:F) sex ratio.
•Males mature at 25 cm length.

70. Breeding of E. tauvina :

•E. tauvina is a protogynous hermaphrodite, females when they reach 650-700 g,
change to male.
•natural males are difficult to get.
•female groupersare artificially transformed to sexual males by male hormone 17α
–methyltestosterone (17 α –MT).
•Oral administration of 17 α –MT at 1 mg/kg b.w. given 3 times a week for 2 months
is effective.

71. •Natural females and sex-reversed males have to be maintained separately.
•Spermiation occurs within 4 months and lasts for at least 4 months after
implantation.
•Females with egg diameter of 0.4 mm are selected and injected with 2 doses of
HCG at 250 IU/kg and a third injection of HCG at 100 IU/kg + salmon pituitary
extract at 10 mg/kg at one day interval.
•Full maturation occurs 52-54 hours after injection.
•Fertilization is carried out artificially using dry method.
•Eggs hatch after 24 hours at 27-30
0
C.

72. Larval rearing:

•The hatchlings are small with extremely small mouth opening and hence cannot
feed on rotifers.
•The first feed can be egg custard (55-60 um particle size) and trochophore larvae
(60-80 um) of green mussel.
•The larvae are obtained by subjecting the mussel to temperature shock treatment.
•CIBA, Chennai is developing a technique for brood-stock development, breeding
and larval rearing of this species.