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VETERINARSKI ARHIV 69 (1), 7-15,
1999

ISSN 1331-8055 Online
ISSN
0372-5480 Printed in Croatia

Non-stripping induced spawning and
double spawning
of grass carp in a hatchery system
with foliage-free brood
diet

Suresh Chandra Rath*, Satya Dev
Gupta,
and Subrata Dasgupta

Central Institute of Freshwater
Aquaculture, Kausalyaganga, Bhubaneswar, India

* Contact address:
Dr. Suresh
Chandra Rath,
Central Institute of Freshwater Aquaculture, Kausalyaganga,
Bhubaneswar, 751002 (Orissa) India,
Phone: 91 674 46 34 21; Fax: 91 674 46
34 07

RATH, S. C., S. D. GUPTA, S. DASGUPTA:
Non-stripping induced spawning and double spawning of grass carp in a hatchery
system with foliage-free brood diet. Vet. arhiv 69, 7-15, 1999.

ABSTRACT

Grass carp, (Ctenopharyngodon
idella (Val.)) could be induced-bred without stripping, by brood diet
manipulation and improved hatchery management practices. Broods reared on a
foliage-free formulated diet (soybean cake, groundnut oil cake, rice bran and
fish meal) were induced-bred and compared with the breeding response of the same
carp, fed with aquatic submerged weed, (Hydrilla verticillata)
ad libitum. The non-stripping breeding response on the non-foliage diet
(NFD) group was 82.2% and over 20.0% response of the brood reared in foliage
diet (FD). Average fecundity, percentage of fertilisation, and spawn recovery
rate of NFD group were recorded as 0.90±0.15×105 vs.
0.47±0.13×105; 89.6±5.33 vs. 68.75±23.1 and 0.76±0.13×105
vs. 0.25±0.08×105 respectively. Broods of the NFD group could be bred
twice and produced spawn at 0.45±0.11×105 per kg body mass within a
time gap of 70 days between two successive breedings. Non-stripping induced
breeding of grass carp is facilitated with mild water current (2-3 m per sec.)
and less water depth (0.5-0.6 m) in a single inlet spawning pool.

Key words: grass carp,
Ctenpharyngodon idella (Val.), non-foliage diet, foliage diet,
Hydrilla verticillata, non-stripping spawning, double breeding

Introduction

The grass carp (Ctenopharyngodon
idella) is basically an aquatic weed feeder. It grows luxuriantly on aquatic
weed and has received considerable attention for its instrumental role in the
biological control of nuisance vegetation. This carp can grow up to 2.5 kg
within a period of six months in a polyculture system (SINHA et al., 1973). This
carp has been introduced world wide from its natural habitats in eastern China
and the former USSR (SHIREMAN and SMITH, 1983). The rationale of introducing
grass carp is to control weeds in an aquatic system and to increase fish
production. As with many other major carp species, the grass carp would not
breed spontaneously in the confined waters of culture ponds, and needing hormone
induction for artificial propagation (LIN, 1965; STANLEY, 1976). The first
induced breeding of grass carp was reported in China in 1960 (KURONUMA, 1968),
followed by the USSR in 1961 (VERIGIN, 1963; VINOGRADOV, 1968). The successful
induced breeding of grass carp introduced into new environments have been
reported during last few decades: Cuttack, India (ALIKUNHI et al., 1962);
Autburn, USA (JEFFREY, 1970); Koncanica, Croatia (FIJAN and VOJTA, 1969); Nepal
(WOYNAROVICH, 1972); Netal, South Africa (PIKE, 1974). Induced breeding of grass
carp by hand-stripping is a world wide practice after KONARDT (1968) of the
USSR. ROTTMANN and SHIREMAN (1979) analysed the problem associated with hand
stripping and dry fertilisation as, (I) inconsistent spawning success due to
improper timing of stripping, (II) poor survival of spent brood due to stripping
stress, (III) excessive requirement. Spawning stress could be minimised by use
of anaesthesia prior to spawning (JEFFREY, 1970; BAILEY and BOYD, 1971, 1973).

SHIREMAN and SMITH (1983) initiated an
investigation into non-stripping spawning and wet fertilisation, which can
reduce brood damage and improve the spawning quality with higher fertilisation
as a potential advantage over stripping. Sporadic success on the non-stripping
induced breeding of grass carp has been recorded in ponds, hapa, tank and pools
(LIN, 1965; CHAUDHURI et al., 1966, 1967; SINGH et al., 1970; TAPIADOR, 1977;
ROTTMANN and SHIREMAN 1979; SELVARAJ et al., 1982; HUSSAIN, 1988; CIFA, 1996,
1998). The present paper deals with the induced spawning of grass carp without
stripping and double breeding in the same season. Breeding without stripping,
and double breeding of grass carp, is based wholly on brood husbandry and
hatchery management practices.

Materials and methods

Six ponds measuring 0.1 ha each were
prepared following standard pond management practices (SINHA, 1972; GUPTA et
al., 1988).

Experimental group

Pond No. I was stocked with grass carp
yearlings (0.4-0.5 kg each) together with four other carp species, viz. Catla
catla, Labeo rohita, Cirrhinus mrigala and Hypophthalmichthys
molitrix in a ratio of 70:10:10:7:3, respectively. The stocking density of
the above ponds was maintained at 1000 kg fish per ha. Here, grass carp was the
principal brood component, other carp forming the maintenance component of the
pond (RATH, 1997). These two ponds were made free from aquatic weed and supplied
with a formulated non-foliage diet. Daily ration was soaked in water and fed at
2-3% of their body mass. Feed was applied in several trays in the column water
of the pond. Broods were reared for two years. 20-30% water of the ponds was
replenished at least once in month from January to March.

Formulated diet

The formulated non-foliage diet (NFD)
contained soybean 50 kg, ground nut oil cake 25 kg, rice bran 20 kg and fish
meal 5 kg in 100 kg feed. The approximate composition of the above feed was
evaluated as crude protein 36.75%; crude fat 6.80%; crude fibre 14.25%; total
ash 13.00%, and nitrogen free extract (NFE) 29.20%; energy was 13.62 kJ/g.

Control group

Pond Nos. III and IV were prepared and
stocked with grass carp and with other carp as listed above. Grass carp were fed
with Hydrilla verticillata ad libitum as a foliage diet. The approximate
composition of the foliage diet was reported as: crude protein 14.1%, crude fat
6.5%, ash 19.3%, crude fibre 6.9%, NFE 46.2%, and gross energy 14.99 kJ per g in
93% dry matter (RAY and DAS, 1994). The water in these ponds was replenished in
the same was as experimental group ponds.

Selection of brood

Maturity status of female broods was
assessed by the simple catheter system (CHAUDHURI et al., 1966). Mature females
other than freshly cathetered individuals were selected for induced breeding. An
equal number of males with free oozing milt showing>90% spermatocrit value in
haematocrit capillaries and centrifuge (GUPTA and RATH, 1991) were selected as
the male brood component for breeding. A total of 35 sets from the FD group and
17 sets from the NFD group were selected for the non-stripping induced breeding
experiment.

Induced breeding

Selected broods were transported to the
breeding pool of the ecohatchery (RATH and GUPTA, 1997) with water in hammocks.
Care was taken to coincide the spawning time to the 28-30 oC
temperature range available on that day. Ovaprim (salomon GnRH and domperidon,
Syndel Laboratoty, Canada) was used as the inducing hormone. Hormone
administered broods were released into the spawning pool. Water current was
provided to the spawning pool by a single inlet system (RATH and GUPTA, 1997)
neither before nor immediately after the hormone administration, but one hour
before the calculated spawning time. Fish bred in the spawning pool within nine
hours of hormone administration without stripping. Non-water-hardened eggs after
each non-stripping breeding were collected from an egg collection chamber,
estimated from its quantity and incubated in a flow-up glass jar system.

Rearing of spent brood

Spent broods were removed from the
spawning pool soon after spawning was over and marked with vital dye (M-procian
blue) following the method of KHAN et al. (1988). They were then transported to
the pond site in a hammock with water and treated with 5 ppm potassium
permanganate solution.

Pond No. V was stocked with the spent
brood of the experimental (NFD) group, and pond No. VI was stocked with the
spent brood of the control (FD) group. Pond management was as described above.
Some of the broods were matured for a second time and were also bred in a
hatchery without stripping.

Spawning efficiency, such as
non-stripping response, fecundity, fertilisation rate, spawn recovery, was
recorded. The significant difference, if any, between the data of both the
groups have been tested by student's t test (SNEDECOR and COCHARAN, 1961).

Results

Matured broods were observed in the
ponds among>2-year age group. During this period individuals in the NFD and
FD groups grew to 2.45±0.40 kg (range, 1.8-3.2 kg, N=15) and 5.02±0.48 kg
(range, 4.5-6.0, N=15) respectively. Female broods in the NFD group showed 88.2%
of non-stripping induced spawning, whereas female broods in the FD group showed
20% non-stripping spawning (Table 1), 31.5% stripping and 48.5% non-response on
induction. Non-responding brood females ejected water through their genital
aperture on attempting stripping. Freshly cathetered females showed poor
spawning response. Spawning started within one hour of initiation of sex play.
Grass carp preferred mild water current (2-3 m per sec) and less water depth
(0.5-0.6 m) in the spawning pool for non-stripping induced breeding. On peak
estruation small, slender and healthy brood showed better coiling courtship over
fatty and heavy broods. It was observed that the fatty brood of the FD group
came closer to each other and expelled their gametes without proper coiling,
even at peak estruation. Fecundity and spawn recovery per unit body mass of the
female was found to be greater in the NFD group compared to FD individuals
(Table 1). The NFD brood could be bred for a second time with a fecundity of
0.66±0.15×105 vs. 90±0.15×105 of the first spawning of its
own (Table 1). Time gap between first and second spawning was recorded as 70
days. Percentage of fertilisation was also observed more in NFD spawning
instances (Table 1).

Table 1. Non-stripping spawning
response of grass carp (Ctenopharyngodon idella) reared on foliage diet
(FD) and non-foliage diet (NFD)

Diet

Breeding

No. of females taken

No. of female bred

% of breeding response

Egg produced 105/kg
body mass±SD (range)

% of fertilisation±SD (range)

Spawn recovery±SD (range)
105/kg body mass

FD

1st

35

7

20.0

0.47±0.13
(0.3-0.7)

68.75±23.1
(33-90)

0.25±0.08
(0.15-0.40)

2nd

9

-

-

-

-

-

NFD

1st

17

15

88.2

0.90±0.15
(0.6-1.1)

89.6±5.33
(74-96)

0.76±0.13
(0.50-0.95)

2nd

7

4

57.1

0.66±0.15
(0.5-0.85)

82.75±6.80
(76-92)

0.45±0.11
(0.35-0.95)

Discussion

On a readily available foliage diet,
grass carp can feed 100%-150% of their body mass equivalent per day (ALIKUNHI
and SUKUMARAN, 1965; CHAUDHURI et al., 1975; SINHA and SAHA, 1980; TRIPATHI and
MISHRA, 1986; ARVINDAKSHAN et al., 1996; SINGH and BOSE, 1997) have recorded a
good somatic growth of grass carp (1.8-2.5 kg) within a one-year period in a
composite culture system by extra foliage diet. SINHA et al. (1973) also
observed growth as high as 2.5 kg in a period of six months, while when fed
ad libitum with Hydrilla verticillata. LIN (1965) opined that
grass carp grows rapidly and accummulates fat with adipose tissue in vegetation
rich ponds. He further commented that such growth acts adversely on gonadal
maturity and spawning. CHEN et al. (1969) reported that exclusive feeding on
Hydrilla could cause extensive mesenteric fat accumulation (even more
than 6% of the body mass) and can have a negative on gonadal maturation and
breeding. The present study supports this observation. FD broods have shown only
51.5% breeding response (including 31.5% hand stripping) over 88.2% of
non-stripping breeding of the NFD group. Protein content of the NFD diet is
evaluated as 36.75% vs. 14% of FD, and may be one of the factors involved in the
above breeding responses. Low fecundity is obvious in the FD group due to huge
somatic growth, and thus the fecundity difference is highly significant between
both groups (P<0.01). The inconsistent and low fertilisation rate of the FD
group (Table 1) may be due to improper coiling courtship which might have
reduced the chances of easy access of male and female gametes. SINGH et al.
(1970) recorded 3.6% success of non-stripping induced breeding (out of 55
female, 9 bred by hand stripping, and 2 bred by non-stripping). CHAUDHURI et al.
(1967) reported 57.8% success of non-stripping induced spawning in a hapa
breeding system (11 bred out of 19). In both cases the body mass of the female
brood was limited to 1.5 kg. The present study reveals that the lower body mass
gives better breeding response and that NFD broods are obviously of lesser body
mass than those of the FD brood. LIN (1965) expressed that a sick spawner always
fail to spawn irrespective of hormone and ripeness of the gonad. Experienced has
shown that freshly cathetered females produce poor spawning results. Despite
their limited success, ROTTMANN and SHIREMAN (1979) stressed the several
advantages of non-stripping induced spawning in a circular pool system.
Undoubtedly, the circular hatchery system and its improved management (RATH and
GUPTA, 1997) facilitated the above breeding programme. It is observed that grass
carp preferred slow water current (2-3 m per sec.) and less water depth (0.5-0.6
m) for effective non-stripping spawning than that of Indian major carps.
Multiple breeding in carp is a new avenue to enhance seed production, given
limited resources. BHOWMICK et al. (1977) reported two spawnings of Indian major
carp by hypophysation under normal pond conditions. GUPTA et al. (1995) could
breed Catla catla as many as four times, wholly based on an improved
brood farming system. They have reported the time gap between two successive
breedings as 30-60 days. HICKLING (1967) presents evidence of two of his
Malaysian grass carp brood which ovulated in May having been ripe again in July
and September respectively. Presently, grass carp could be bred four times,
based on non-foliage diet with a time gap of 70 days between two successive
breedings. At this juncture we are unable to comment further, except to report
on the non-stripping spawning efficacy of the NFD group, unless a standard
balanced diet is formulated. Work in this regard is in progress.

Conclusion

From the above study it appears that
non-foliage diet and improved hatchery management practices facilitate the
non-stripping induced spawning of grass carp to promote seed production.

Acknowledgements
The authors are
grateful to Dr. S. Ayyappan, Director of the Central Institute of Freshwater
Aquaculture, for his keen interest and for providing facilities to execute this
work. Thanks are due to Dr. C. S. Purushothaman, Senior Scientist CIFA, for his
critical appraisal of the manuscript. Thanks are also due to Shri n. k. Acharya,
Technical Officer, and Miss Bithi Mandal, SRF CIFA, for their help in data
analysis and manuscript preparation respectively.

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Received: 17 February 1998
Accepted:
15 January 1999

RATH, S. C., S. D. GUPTA, S. DASGUPTA:
Potaknuto slobodno mrijescenje i dvostruko mrijescenje bijelog amura u
mrijestilistu hranjenog smjesom bez prirodne hrane. Vet. arhiv 69, 7-15, 1999.

SAZETAK

U bijelog amura (Ctenopharyngodon
idella, Val.) moze se upravljanjem nacinom hranidbe i poboljsanim vodenjem
mrijestilista potaknuti slobodno mrijescenje. Kod matica hranjenih smjesom bez
prirodne hrane (sojina i kikiriki pogaca, rizine mekinje i riblje brasno)
izazvano je mrijescenje i usporedeno s mrijescenjem jednakih matica bijelih
amura hranjenih ad libitum vodenim biljem (Hydrilla
verticilliata). Uspjeh slobodnog mrijescenja skupine bez biljne hrane bio je
82.2%, a u matica hranjenih vodenim biljem 20.0%. Prosjecna plodnost, postotak
oplodnje i prezivljavanje mlada odnosili su se u matica hranjenih bez prirodne
hrane prema istome u matica hranjenih vodenim biljem kao
0.90±0.15×105 prema 0.47±0.13×105, 89.6±5.33 prema
68.8±23.1 i 0.76±0.13×105 prema 0.25±0.08×105. Matice
hranjene bez prirodne hrane mogle su se mrijestiti dvaput i davati
0.45±0.11×105 kg mlada po kg tjelesne mase s razmakom od 70 dana
izmedu dva uzastopna mrijesta. Potaknuto slobodno mrijescenje bijelog amura
pospjeseno je blagim strujanjem vode (2-3 m u sekundi) i manjom dubinom vode
(0.5-0.6 m) u zajednickom bazenu za mrijescenje.

Kljucne rijeci: bijeli amur,
Ctenopharyngodon idella (Val.), smjesa bez prirodne hrane, prirodna hrana,
Hydrilla verticilliata, slobodno mrijescenje, dvostruko mrijescenje

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