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.


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


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).


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)



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
































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.


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.

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.


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