Synergistic Approach - an Alternative to High-Cost Aquaculture

Central Institute of Freshwater Aquaculture (CIFA)
Dhauli, Kausalyagang, Bhubaneswar

NETWORK OF AQUACULTURE CENTRES IN ASIA
BANGKOK, THAILAND

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SYNERGISTIZ APPROACH - AN ALTERNATIVE TO HIGH-COST AQUACULTURE*

S. D. Tripathi¹ and D. N. Mishra²

¹   Main Centre, All India Coordinated Research Project on Composite Fish Culture. Fish Seed Production, Freshwater Aquaculture Research and Training Centre P. O. Kaushlyagang 751002, Orissa (India)

²   Uttar Pradesh Sub-centre of the All India Coordinated Research Project on Composite Fish Culture and Fish Seed Production, 334, Husainabad, Jaunpur (Uttar Pradesh)

* Paper was presented before the International Symposium on Aquaculture of carp and related species, Paris 2–5 Sept., 1985

Abstract

The package of modern aquaculture practices involves high-cost technologies. However, there is an increasing awareness towards development of low-cost, energy-saving, systems and several efforts have been directed towards achieving this goal during the recent past. Measures such as reduction in the rate of stocking densities and elimination of the feed component have been adopted coupled with low/reduced targets of production.

In addition to these known approaches, a novel synergistic approach has been adopted with high targets of production in the experiments conducted at the Jaunpur Centre of the All India Coordinated Research Project on Composite Fish Culture and Fish Seed Production. Using either phosphatic or nitrogenous fertilisers and aquatic weeds, yields of the order of 2 609–3 330 and 3 642 – 3 966 kg/ha in 9 months have been realied at input costs of Rs 1.13 - Rs 1.77 (US$ 0.09–0.15) but even higher yields ranging from 4 074 kg/ha/ 9 months to 4 480 kg/ha/yr have been obtained with aquatic weeds alone at at remarkably low input costs of Rs 0.93 - Rs 1.42 (US$ 0.08–0.12) per per kilogram of fish suggesting that the newly developed, low cost, labour intensive, technology could be recommended for extensive adoption in the rural areas, especially in the Third World where submerged aquatic vegetation such as Hydrilla, Potamogeton and Ceratophyllum or terrestrial vegetation like grasses or fodder are abundantly available.

Introduction

The development of carp polyculture system-called composite fish culture in India - has raised the productivity of fish ponds by 8–16 times over the traditional yields of about 600 kg/ha/yr but the package prevides a high-cost technology, feed alone constituting 67% of the total production cost (Tripathi and Ranadhir, 1982). While a search for alternate/appropriate technologies is on to achieving moderate yields at low costs, obviously involving reduced rates of stocking and elimination of the costly feed component, recent experiments based on a synergistic and ecological approach using either nitrogenous or phosphatic fertilizers and aquatic weeds or aquatic weed alone realized high rates of production at low operational costs at the Jaunpur (Uttar Pradesh) Centre of the All India Coordinated Research Project on Composite Fish Culture and Fish Seed Production. These experiments are discussed in the present communication.

Materials and Methods

In the first series, the experiments on the use of fertilizers for increased yields were conducted during March-December, 1981 and 1982 in two 0.1 ha ponds (NP 15 and NP 16) having an average water depth of 1 m. The ponds were prepared using a local toxicant, oil-cake of mahua (Bassia laticolia), at 250 ppm and stocked at 5 000 fingerlings/ha with a mixed population of ecologically different species comprising six Asiatic carps, three indigenous (Catla catla Ham., Labeo rohita Ham., and Cirrhinus mrigala Ham.) and three exotic (Hypophthalmichthys molitrix, Ctenopharyngodon idella Cuv. and Val. and Cyprinus carpio var. communis Linn.) Table I). During 1981 MP 15 was fertilized with single superphosphate at 713 kg/ha while NP 16 with cattle-dung and urea at 7 500 kg and 225 kg/ha respectively at about 10-day intervals. Since the oil cake is also a rich fertilizer, no fertilizer was added till after a fortnight of stocking. Grass carp were fed daily on aquatic vegetation (Hydrilla verticillate, Ceratophyllum demersom and Potamogeton sp.) and chopped terrestrial grasses and about 11 894 kg in NP 15 and 11 339 kg in NP 16 comprising 76% aquatic and 24% terrestrial vegetation used during the experiment.

During 1982, fertilizer application was reversed, NP 15 being fertilized with cattle-dung and urea at 8 400 kg and 270 kg/ha respectively and NP 16 with single superphosphate at 756 kg/ha from the day of stocking itself at regular 8-day intervals. Gras carps were fed daily with Hydrilla and land vegetation, using ll 866 kg (Hydrilla 41%) in each pond during the rearing period.

Table I Stocking, survival, growth and yield of fish in ponds treated with nitrogenous phosphatic fertilizers

* Excluding labour costs

Table II Plankton and benthic production in ponds treated with nitrogenous/phosphatic fertilizers

* Treated with phosphatic fertilizer
** Treated with nitrogenous fertilizer

In the second series, only a single 0.07 - ha pond (NP 10), prepared in a similar manner as in the first series, was stocked with the same combination of Asiatic carps but in a different proportion and density, C. idella constituting 50% of the total stock while each of the remaining five species 10% of the total density of 4 00 fingerlings/ha. Diring 1983–84, certain soil corrective measures were undertaken and lime applied at 945 kg/ha at weekly intervals to contain any excess of carbon-di-oxide and help quick mineralisation of undigested faecal matter. Grass carp were fed daily and a total of 12 975 kg of weeds (Hydrilla, 66%) provided during the rearing period covering one full year. During 1984–85, the experiaent was undertaken in a different 0.07-ha pond (NP but wound up ahead of schedule limiting the rearing period to 295 days. No soil correction measures were taken and lime used only at 268 kg/ha, earlier at monthly and later, during winter days, at weekly intervals. About 15 947 kg of weeds (83% Hydrilla and 17% terrestrial grasses) were used. The water level in the two ponds ranged from 83–130 cm.

Data on water quality, plankton and benthos were recorded biweekly while data on fish growth at monthly intervals. Soil quality was studied every three months.

Results and Discussion

First Series

These experiments show that the growth of all the species is slightly better with nitrogenous than phosphatic fertilizers (Table I), both plankton and benthic production being high in ponds fertilized with nitrogen (Table II) tend to support the support the trend in growth noticed here. However, the overall growth of C. catla and C. carpio is quite poor even with nitrogenous fertilizers. Of all the indigenous apecies, C. mrigala registered the maximum growth (646–740 g) and appears to show a preference for phosphatic fertilizer. With survival ranging from 97–100%, the feed conversion rate of 124.8 and 115.7 during 1981 and 73.7 and 95.7 during 1982 in NP 15 and 16 respectively suggests that the poor growth performance of grass carp in 1981 is probably due to a high moisture content of the weeds as a greater bulk (75%) was of aquatic origin. The reasons for the poor growth of C. carpio in both the phosphorus and nitrogen-treated ponds in 1982 are, however, not clear despite its comparatively large size at stocking.

There is a strong opinion against nitrogenous fertilization of fish ponds since nitrogen is fixed by bacteria in adequate quantities. Any addition of nitrogen from extraneous sources not only disturbs the state of aquilibrium existing in nature by stimulating the growth of denitrifying bacteria but also does not help in its utilization by phytoplankton (Hepher, 1952). El Samra and Olah (1980) found that nitrogen fixation in fertilized fish ponds was far too low than natural lakes. Sinha et al. (1980) observed that due to a low nitrogen exploitation officiency (5.5% to 30.67%) of the carps employed in composite fish culture, a large nitrogen balance existed in the pond raising serious doubts whether nitrogenous fertilisation is at all necessary especially in ponds provided with supplementary feed.

Hickling (1962) considered nitrogen a poor fertiliser than phosphorus and Rabanal (1967) did not find any decrease in fish production without nitrogen. Though no information on phosphatic fertilization alone in Indian conditions, where the pond soils are generally poor in organic carbon as well as nitrogen and phosphorus (Banerjea, 1967), is available, a comparison of the data on mean growth by ‘t’ test in the present study does not indicate significant differences (P> 0.05) in nitrogen and phosphorus treatments within and between years. However, the study does not partition the role of the faecal release of nutrients and phosphorus in cattle-dung.

The residual effect of nitrogenous fertilisers is almost nil but Probst (1950, cited by Hickling 1962) indicated that a pond will give a 92% increase in yield over an unfertilised control even after one year of phosphate fertilization. The reverse treatments in 1982 in the present series do not indicate the residual effects of either.

Second Series

Since C. idella itself is known to play a great role in fertilising fish ponds and thereby increasing production, the second series was designed to assess this contribution. As the various species were found to register a very fast growth, a different strategy was adopted to obtain high yields. Fish that attained a weight of 1 kg or more were skimmed and replenished with an equal number of fingerlings of the same species. With soil correction and about the same quantity of aquatic/terrestrial vegetation as in the fertiliser series, not only a much higher yield rate was achieved but four species viz. G. catla, H. molitrix, C. idella and C. carpio registered average weights of over 1 kg in 5–8 months (Fig. 1 a) whereas non of the species except H. molitrix and C. idella had attained an average weight of over 1 kg in the first series.

Fig. 1. Growth pattern of Asian carps based on faccal release of grass carp. (a) First experiment, (b) Second experiment. SC : H.molitrix, CC :C. carpio, C:C. catla, GC : C. idella, R : L. rohita, M : C. mrigala. First crop of 1-kg fish (I), second crop of 500-g fish (II).

A comparison of plankton and benthic production (Table III) in the two series shows the dominance of phytoplankton, rotifers and Chironomus in the latter which accounts for the faster growth of H. molitrix, C. catla and C. carpio. Based on the total weed consumed, a conversion ration of 94.12 and 120.1 was estimated for C. idella during 1983–84 and 1984–85 respectively.

The growth rates of different species in NP 10 and 8 are shown in Fig. 1 a and b. Though the two experiments were initiated in different months, March 1983 and June 1984, the total yield does not appear to vary (NP 10 : 4480 kg/ha/yr; NP 8 : 4074 kg/ha/295 days). It appears that the yield from NP 8 would have been higher than NP 10, had the experiment continued for one full year. Earlier observations by the senior author (S.D.T.) had shown that while C. carpio gained a weight of 29.3% in 60 days, C. mrigala gained only 7.5% in 30 days under laboratory conditions when reared on the faecal release of grass carp Barrackpore, 1979). In the present series too, but for C. mrigala and L. rohita, which attained a weight of about 500 g only in one year, all the other species in the system performed well, H. molitrix yielding two crops of 1 kg fish. Of the two crops of C. carpio, the first crop comprised 1 kg fish and the second over 500 g each. A similar pattern is observed in NP 8, though the second crop of over 500 g C. catla and H. molitrix could not be obtained owing to unscheduled termination of the experiment but the average weights of 242 g and 421 g on 31 March 1985 clearly indicate that average weights of 500 g were easily possible with rising temperatures in the next 70 days and the system could thus be run on a continuous “put and take” basis. The cost of production, excluding labour, was calculated to be Rs 1.42 (US$ 0.08) /kg of fish in NP 10 and NP 8 respectively.

The system is thus highly profitable, especially making was of very small and shallow ponds which abound in the countryside where such a fast growth rate was not registered before even with supplementary feed, and appears to be an appropriate model for the Third World countries with Hydrilla or other aquatic/terrestrial vegetation available in plenty. “Feed a grass carp well and you feed three other fish” is a well-known adage. The Chinese farmers stock 50–60% grass carp, 20–30% big-head and 20% silver carp in Malaya (Gopinath, 1950). Employing the three exotic carps vis. H. molitrix, G. idella, and C. carpio at 3 700 fingerlings ha in the proportion of 4: 2: 3 and using aquatic weeds alone, Singh et al. (1972), obtained a production of 2896 and 2922 kg/ha/yr, the average weight of the three species being H. molitrix 1170 – 1200 g, G. idella 639–680 g and C. carpio 419–450 g.

Van der Lingen (1957, cited by Hickling, 1962) has observed that no further growth is realised once the level of maximum standing crop is reached but till such time the growth is fast and the gain in weight most rapid. Yashouv (1959) noted that the daily fish production decreases when the fish biomass approaches the carrying capacity. The effect of the total biomass on the carrying capacity of the pond with reference to each species in the present series is shown in Fig. l a and b. Tripathi (1984) has recently examined the inter and intra-specific competition or density-dependent growth among various species in composite fish culture and suggested skimming as the best way to increase production and reduce risk.

Acknowledgements

The authors are grateful to Dr. A. V. Natarajan, Director, Central Inland Fisheries Research Institute, Barrackpore, and Mr. A. N. Singh, Director of Fisheries, Government of Uttar Pradesh, for affording necessary facilities and to Dr. V.R.P. Sinha, Head, Freshwater Aquaculture Research and Training Centre, Kausalyagang, for his keen interest in the work.

Table III Plankton and benthos of polyculture ponds with grass carp as the main component

References

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Barrackpore, 1979. Final Report. CIFRI/IDRC Rural Aquaculture Project Central Inland Fisheries Research Institute, Barrackpore. Special Report No. 1, 250 pp.

EL Samra, M. I. and Olah, J., 1980. Magnitude and pattern of nitrogen fixation in fish ponds. Aquaculture Hungarica (Szarvas), 2: 94 – 104.

Gopinath, K., 1950. Freshwater fish farming in Malay Archipelage. J. Zool. Soc. India, 2: 101 – 108.

Hepher, B., 1952. The fertilization of fish ponds 2. Nitrogen Bamidgeh, 4(10–12): 220 – 223.

Hickling, C. F., 1962. Fish culture. Faber and Faber, London: 295 pp.

Rabanal, H. R. 1967. Inorganic fertilizers for pond fish culture. FAO Fish. Rep., (44) Vol. 3: 164 – 179.

Singh, S. B., Sukumaran, K. K., Chakrabarti, P. C. and Bagchi, M. M, 1972. Observations on composite fish culture of exotic carps. J. Inland Fish. Soc. India, 4: 38 – 50.

Sinha, V.R.P., Khan, H. A., Chakrabarty, D. P. and Gupta, M. V. 1980. Preliminary observations on nitrogen balance of some ponds under composite fish culture. Aquaculture Hungarica (Szarvas), 2: 105–116.

Tripathi, S. D. and Banadhir, M, 1982. An economic analysis of composite fish culture in India, pages 90–96 in Aquaculture Economics Research in Asia: proceeding of a workshop held in Singapore. 2–5 June 1981. Ottawa, Ont., IDRC. 1982.

Tripathi, S. D., 1984. Report of the Project Coordinator, pages 195–213. In Seventh Workshop on All India Coordinated Research Project on Composite Fish Culture and Fish Seed Production held at Allahabad. 5–6 May, 1984. Freshwater Aquaculture Research and Training Centre, Kausalyagang, Orissa.

Yashouv, A, 1968. Mixed fish culture - An ecological appreach to increase pond productivity. FAO Fish Rép., (44) Vol. 4 : 258–273.