Giant freshwater prawn seed production starts in Andaman - INDIA - A scientist and his team of the Division of Fisheries Science, Central Agricultural Research Institute (CARI), Port Blair, have initiated research on breeding and larval rearing of Giant Freshwater Prawn (M Rosenbergii) under controlled conditions at the CARI farm complex.

1. SEED PRODUCTION OF GIANT
FRESHWATER PRAWN
Ashish sahu

2. CONTENT
 INTRODUCTION
 REPRODUTIVE BIOLOGY
 BREEDING SEASON AND CHARACTERISTIC
 REPRODUCTIVE SYSTEM
 DEVELOPMENT OF LARVAE
 LARVAL REARING UNIT

3. LARVAL BIHAVIOUR
LARVAL FEEDING
ARTEMIA HATCHING UNIT
POST LARVAL HOLDING UNIT
PROPHYLACTIC TREATMENT

4. INTRODUCTION
 Macrobrachium rosenbergii commanlly called as
scampy, is the giant fresh water prawn.
 They are found in tropical and subtropical All farmed
freshwater prawns belong to the genus
Macrobrachium. The largest species in the genus is
Macrobrachium rosenbergii.
 Areas of the world out of which 49 species are of
fisheries importance and 15 species are of culture
significant.
 They are found in inland fresh water areas including-
lakes, rivers, swamps, canals, ponds and also in
estuarine areas.
 Species that grow to large size are M.rosenbergii,
M.americanum and M.carcinum. Macrobrachium
rosenbergii.

6. The giant fresh water prawn in nocturnal in
habit, found hiding under shads and shelter
during day time.
They are found in extremely turbid condition
being an omnivorous bottom feeder.
They are found in varying salinities such as 0-
25ppt and temperature varying from 25ºc to
34ºc.
Male grow faster than female.

7. Reproductive biology
Age at first sexual maturity
 Scampi has been reported to attain first sexual
maturity on reaching a length of 140-150mm and at
35-40gm weight.
Sexual dimorphism
Male Female
•Mature male are larger,
second walking leg
much larger and thicker.
•Cephalothorax is larger
but abdomen is narrow.
Smaller in body size, the
second walking leg thinner
and shorter.
Cephalothorax is smaller,
abdomen is broader.

8. base of 5th walking leg.
•Ventral side of the first
abdominal segment has
a lump a hard point at
the centre which can be
felt with finger.
•Pleura of the abdomen
is shorter.
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10. Courtship, Mating, Spawning
 Copulation is known as mating that takes place
between hard shelled males and mature soft shelled
female.
 The time period between moulting and mating varies
from 1.2 to 21.8 hours (average 9.1 hours).
 Male to contact females by its antenna and claws once
the contact is established the male turns the female
upside down, clears her thoracic region by his
pereopods and male gonopore is brought close to
sperm receptacle of female.
 The transfer of spermatopore takes only a few
seconds and it is accomplished by first two pleopods
of male.
 The eggs laid by the female are fertilized by sperm
attached to the underside of thorax.

12.  The fertilized eggs are transferred to the ventral side of
the abdomen ( brood chamber) by ovipository setae
and the same is attached to the ovigirous setae of 1st
four pleopods and kept in the place by a membrane.
 Movements of the pleopods helps in aerating the eggs.
 Fecundity varies from 20000-100000 eggs.
 Adult female carrying eggs on the ventral side of
abdomen are called berried female.
 The eggs are slightly eliptical (0.6- 0.7mm in the long
axis) bright orange in colour, 2-3 days before hatching
, it turns grey black in colour

13. Breeding season
 Mating and reproduction are reported throughout the
year in farm reared ponds.
 Minimum number of berried females noticed during
December to January.
 In India in natural waters the breeding season of
Hooghly stock is reported to be from December to July
with the peak being, March to May.
 In Kerala backwaters it is from July to December with
the peak in October and November.
 In Andhra Pradesh [Kollerulake and Godavari system],
it is throughout the year with peak in August to
October.

15. Reproductive System
Male
 Have a pair of fused testis located on the mid dorsal
side of the cephalothorax below carapace.
Female
 Have a pair of ovaries that are located dorsal to the
stomach and hepatopancreas in cephalothorax cavity.
 the oviduct arise laterally and it opens on coxa of 3rd
pereopods.
 Maturity stage of the ovary can be seen though
carapace through external examination from the colour
of the ovary and size in relation to carapace cavity.
 Four stage such as

16. Immature (neuter period)
Early maturing phase
Late maturing phase
Ripe phase
a) Immature (neuter period)
During this period ovary is very small
transparent seen in the posterior most region of
the carapace cavity.
Oocytes are 0.064 to 0.128mm in diameter,
spherical with large nucleus.


17. b) Early maturing phase
 In this phase, ovary grows to accupied 1/4 to 1/2 of the
total carapace cavity.
 Colour is yellowish due to light deposition of yolk in the
cytoplasm.
 Oocytes are 0.191 to 0.447 mm in diameter and
nucleus is not large.
c) Late maturing phase
 During this phase ovary accupies ¾ of the carapace
cavity.
 Ovary is light orange in colour, due to heavier
deposition of yolk in the cytoplasm.
 Ova size range from 0.319 to 0.574 mm.

18. d) Ripe phase
In this phase ovary occupies the entire
carapace cavity.
Colour turns dark orange, ova opaque due to
heavy yolk.
Oocytes diameter varies from 0.4468 to 0.7761
mm.
Development of ovary take place within 15 to 20
days.

19. Development of larvae
 The newly hatched zoea larva is about 1.92mm in
length.
 It has the zoeal characteristics such as- a body
distinguis- hable into cephalothorax and abdomen.
 All cephalic and thoracic appendages are present.
 The larvae passes though 11 zoeal stages within a
period of 23-32 days depending on the environmental
condition.
 The distinguishable features of 11 zoeal stages is it is
represented in following table


20. Larval
stage
Age
(days)
Total length(mm) Distinguishing features
I. -
II. -
III. -
IV. -
V. -
VI. -
VII.-
VIII.-
IX. -
X. -
XI. -
Post
larva
e
1
2
3
4-6
5-8
7-10
11-17
14-19
15-22
17-24
19-26
23-27
1.92
1.99
2.14
2.5
2.8
3.75
4.06
4.68
6.07
7.05
7.73
7.69
Sessile eye.
Stalked eye.
Uropod present.
Two dorsal rostral teeth uropod
biramous with setae.
Telson narrow, elongated.
Pleopod buds appears.
Pleopods biramous and bare.
Pleopod with setae.
Endopods of pleopods with
appendix interna.
Three to four dorsal rostral
teeth.
Teeth on half of the upper
dorsal margin.
Teeth on upper and lower
margin of rostrum, adult
behaviour.

22. Hatchery technology
 The following are the different units of a fresh water
prawn hatchery.
a. Brood stock rearing unit.
b. Incubation and spawning unit.
c. Larval rearing unit.
d. Post larval holding unit.
A .Maintenance of brood stock
 For developing a brood stock early juveniles are
stocked in the ponds @ of 3-4 /m2 and adults @ of 2
nos. /m2.
 The sex ratio can be 1:4 (male: female).
 Size may vary from 0.2 ha- 1.6 ha with an average
depth of 0.9m ( minimum 0.75 and maximum 1.2m) .

23.  The bottom of the pond should be smooth with the
slop from water intake towards the drain (slop of 1:500
for larger pond and 1:200 for smaller pond).
 Though culture has been successfully done in saline
water (salinity range 10ppt to 25ppt) growth rate is
lesser in harder water.
 Optimum pH can be 7 to 8.5 and optimum temperature
29c to 31c.
 For hatchery purpose, healthy and active berried
females are chosen.
 The prawn can be fed on pelleted feed containing 35-
40% protein.
 They are fed 3-4% of the total body weight about 3
times per day. Prawn attain maturity with in 4-7
months.

25. Incubation and hatching unit
 The berried females bearing dark grey coloured eggs
in the abdomen are utilized for incubation and
hatching.
 the berried female are first disinfected by placing then
in fresh water containing 0.3 ppm copper sulphate or
15-20 ppm formalin and released into the larval rearing
tank having 5 ppt salinity @ of 5 nos /m2 or
maintained in a hatching tank.
 Egg hatching takes place usually during night time
normally.
 Soon after hatching is completed, mother prawn are
carefully scooped out.
 Usually, berried females are not fed during 2-3 days of
incubation to avoid deterioration of water quality.

26. Larval rearing unit
 Following factors of effecting on larval rearing
a) Salinity
b) Quality of larval rearing tank
c) Temperature
d) Dissolved oxygen
e) pH
f) Water exchange
g) Exposure to sun light
h) Stocking density of larvae
i) Larval behaviour
j) Larval feeding
k) Mode of feeding

27. a. Salinity
 For good growth and survival of larva are required
12ppt of salinity.
Larval stage Optimum
salinity (ppt)
1stb and 2nd 20
3rd to 5th 14
6th to 7th 10-12
8th to 11 10

28. B. Quality of larval rearing tank
 Zink and copper sulphate and there allows, galvanized
steel bare concrete and oil are toxic to fresh water
prawn larvae.
 If concrete is used, inner surface should be coated
with several layers of epoxy resin to prevent harmful
chemical leaking out of concrete and to provide
smooth surface.
c. Temperature
 Temperature is a key factor that mostly responsible for
good growth and moulting of larvae.
 Optimum temperature for larval rearing as 29-31c.
 Temperature below 25ºc and above 33ºc are
detrimental for the larval growth, feeding activity and
survible.

29. d. Dissolved oxygen
 Dissolved oxygen has to be maintained at saturation
level by aeration.
 Aeration also helps in expelling certain amount of
ammonia from the water and even distribution of
temperature.
e. pH
 The pH has to be maintain at a level of 7-8.5, the ideal
being 7.
 At higher ph, unionized ammonia (NH3) increases
which is toxic to larvae.
 Ammonia concentration should not exceed 1.5 ppm of
NH4 + and 0.1 ppm of NH3

30. f. Water exchange
 50% of water is daily exchange after cleaning of tank
and before feeding the artemia nauplii.
 Provision to be made for supplying clean, pollutant
free filtered water.
g. Exposure to sunlight
 Exposure to sunlight shall help in augmenting
biological purification of water by algae.
 Direct exposure is harmful for larvae.
 Algal supplement has been shown to have beneficial
role by increasing growth rate, survival rate and
reducing the duration of larval cycle.
 A two phase larval rearing system have been
recommended.

31.  In phase 1st i’e for rearing larvae from stage 1st to 5th
cylindro-conical tank of 1000 litres made of fibres glass
are used.
 Inner surface of these tanks should be smooth painted
dark green.
 For rearing larval stage from 5/6 to 11 rectangular
cement tanks with flat or “U” shaped bottom are used.
 tank should have water inlet and outlet facilities.
 It should be 14 m2 in size with one meter depth to hold
70 cm deep water.
 Stocking density of larvae-In the 1st phase larvae can
be stocked at 500-700 nos per litre where as in second
phase it can be 50-80 larvae/ litre.

32. h. Larval behaviour
 The newly hatched prawn larvae (zoea) are planktonic
and they swim tail first ventral side upwards and head
down at an oblique angle.
 They are attracted towards light during early larval
stages.
 Swimming close to the surface of the water in groups.
 As the larvae grows to post larvae, there is radical
changes in behaviour, swimming freely in water, they
crawl or cling to the tank surface.
 The post larvae do not need brackish water but it can
be maintain in fresh water.
 First post larva is usually observed 20 days after
hatching (between 22and 27 days) and 90% develop
to post larva within next ten days.

33. Larval feeding
 Most commonly larva used are live feed for our rearing
as artemia nauplii.
 During recent year zooplankton such as Moina, cut
pieces of Tubifex worm/ Acetes / Lamllidens and
prepared feeds are used as feed for macrobrachium
larvae.
 Quantity of artemia nauplii to be given at different
stages vary at noted below in table-

34. Feeding rate of Artemia nauplii to prawn
larvae
Age of larvae
(days)
Larval stage No. of
AN/larva/day
4
5-6
7-8
9
10-11
12
13-14
15-24
25-30
31-35
2nd-3rd
3rd-4th
4th-5th
4th-6th
5th-7th
6th-7th
6th-8th
7th-PL
8th-PL
9th-PL
10
15
20
30
35
40
45
50
40
30

35. CIFA are developed two types of prepared
feed’s method for rearing larvae of
macrobrachium I’e following-
Type 1st
Percentage
(by weight)
1.
2.
3.
4.
Fresh water mussel meat
( foot and gonad)
Hen’s eggs.
Skimmed milk powder.
Vitamin mineral mix
68
2
0

36. Type 2nd
Percentage
(by weight)
1.
2.
3.
4.
5.
Flesh of fish (channa)
Hen’s of eggs
Wheat flour
Skimmed milk powder
Vitamin mineral mix
68
20
5
5
2

37. Mode of feeding
 Feeding start from 2nd day of hatching.
 Prepared feed are usually given in the day
time,artemia nauplii in the night time.
 Different stages require 50-150µg prepared feed
/larva/day and artemia nauplii from 5-50 /larvae /day.
Artemia hatching unit
 Artemia cyst production on a commercial scale is
taken up at different places by multinational and the
same are available in sealed can for hatchery use .
 When these stored cysts are soaked in sea water,
embryonic development is resumed and a nauplius
larva hatches out within 24-36hours.
 To achieve optimum level of hatching, the following are
-

38. Salinity
 It is to be maintained between 15-35ppt.
 One g cyst can be soaked in 1litre (not more than
2gm/litre) for better hatching efficiency.
Aeration
Vigorous aeration @ 10-20 litre air per minute
required for the developing cysts so that oxygen
level should be nearer to saturation.
Temperature
 Ideal temperature can be from 25ºc to 32ºc.
pH of the medium
 Desirable pH is between 8 to 8.5. This is accomplished
adding 1gm sodium bicarbonate in 1litre of water.

40. Illumination
 Illumination has to be not less than 1000 lux (2000 lux
at water surface preferred).
 After 15-20 hours of hydration, the cyst shall burst,
pre-nauplius surrounded by hatching membranes
become visible.
 The embryo comes out of the shell and hangs
underneath the empty shell. This is the umbrella stage.
 Soon after hatching membrane breaks, and free
swimming nauplii larva emerges.
 The newly hatched nauplius is 400-500µ in length.
 The nauplii do not feed for about 12 hours. After 12
hours, it starts feeding on algal, cells, bacteria and
detritus of 1-40µ size. After 15 moults it becomes
adult.

41. Prophylactic treatment
 Antibiotics are mostly used as prophylactic or
therapeutic by farmers.
 Some important antibiotics are following that currently
used in systemic treatment in India.
 Oxytetracycline
 Chloroteracycline
 Doxycycline
 Furazolidone
 Sulphadiazine +Trimethoprim
 Nitrofurazone+Furazolidone etc.