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Higher Stocking Densities and Azolla Integration, a Means to Increase Fish Production and Income from Integrated Rice-fish Culture

G. C. Haldar
Bangladesh Fisheries Research Institute, Riverine Station, Chandpur, Bangladesh.

D. A. Jahan
Bangladesh Fisheries Research Institute, Riverine Station, Chandpur, Bangladesh.

M. Ali
Agricultural Extension Officer
Department of Agriculture Extension, Chandpur.

Abstract/ Executive Summary:

Experiments were conducted to study the impact of higher stocking densities and Azolla integration on the production and income generation of rice-fish farmers. Monoculture of Rajpunti, (Barbodes gonionotus) at 3 stocking densities; 5000 (T₁), 7500 (T₂) and 10000 (T₃)) ha^-1 were done in the farmers' rice plots of Chandpur district as on-farm research. In the treatment, T₂ and T₃along with usual rice bran feeding, Azolla was integrated as supplemental feed. The highest fish production (521.20 kg) and net income (TK 23537.50) and the lowest fish production (320.16 kg) and net income (TK 14540.0) ha^-1 was obtained from T₃and T₁ respectively. Though stocked at a higher density, no adverse effects on the survival and growth of the stocked fishes and soil and water quality of the rice plots were observed. The result indicated that the higher stocking density with Azolla integration may be advocated to increase fish production and farmer's income from rice-fish culture in Bangladesh.

Keywords: Rice-fish culture, Rice-Fish-Azolla integration, Integrated farming

Location: Matlab, Hajiganj and Chandpur Sadar

Start Date: 00-07-1999

End Date: 00-10-1999

Program Area: Resource Development and Management

Commodity: Aquatic animal

Objectives:

To evaluate the impact of higher stocking densities and Azolla integration in rice-fish culture.

Methodology:

The study was conducted in 16 farmers' plots with three replication each during aman (kharif-2) season in three upazilas (Matlab, Hajiganj and Chandpur Sudar) of Chandpur District, Bangladesh during 1999 under Bangladesh Fisheries Research Institute, Riverine Station Chandpur. Rice plot preparation involved strengthening and raising of the dykes by about 20 to 25 em and excavation of a small ditch or swamp us refuge for fishes. The refuges were constructed in an average size of 30-40 m² with 60-70 cm depth. Area of the ditches varied from 2.0-7.5 % of the total rice plots, except a few, which already had small ditches adjacent to the rice plot. Bamboo twig and bamboo slips were installed in the refuge to prevent fish from being poached and from predators. The fields were ploughed as they were usually done for rice cultivation. A basal fertilizer dose of urea, triple super phosphate (TSP), murate of potash (MP), gypsum and zinc were applied @ 150, 100, 70, 60 and 10 kg ha^-1 respectively. The integrated farmers followed normal rice farming with two rice. Aman rice (varieties, BR-22 and BR-23) were transplanted during late July to August employing line plantation process and no weeding was done. The water temperature, water level, dissolved oxygen, pH, NH₃ and water hardness of the rice plots were measured by HACH water testing kit. Soil samples from the cultured plots and samples from the adjacent plots were collected following the standard soil sample collection procedure. The soil samples were analyzed from the Soil Resource Development Institute, Regional Sub-Station at Comilla. Monoculture of Rajpunti (B. gonionotus) was done at three stocking densities, viz. 5000 (T₁), 7500 (T₂) and 10000 (T₃) ha^-1 with a control of only rice. Fingerlings were stocked 12-15 days after the rice plantation when the water in the rice plot had a minimum depth of 8-10 cm and a few new sterns of rice plant were grown. At the time of stocking, initial length and weight of the fingerlings were measured. The details of stocking density, average size at stocking etc are given. Fishes of all the 3 treatments were fed with rice bran @ of 2% body weight daily. To adjust feed requirements, monthly sampling was done using a cast net. The length and weight of the fishes were recorded and accordingly feed requirement was calculated. In treatments 2 and 3, duckweed (Azolla sp.) was supplied up to satiation of the stocked fishes. Usually the duck weeds were provided continuously as feed to the stocked fishes and placed within a rectangular bamboo frame in the refuge or ditches of the rice plots. Dykes and drains were repaired during the culture period as and when needed and water level of the rice plots was maintained at 18.2 to 22.2 cm. The fishes of the plots were harvested before rice harvesting or immediately after the harvest of rice by cast net and then dewatering the plots and refuge ponds.

Source of Information: J. Inland Fish. Soc. India, 35 (2) : 1-6, 2003

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Rice production of the plots of higher stocking densities and Azolla integration (T₁_andT₃) were also higher than T_1, with lower stocking densities. Soil pH treatment T₂ and T₃was little higher than the control plots. Organic matter and potassium content of the fish cultured plots were also higher than the control plots. Fish culture in rice plots may have some positive effects on organic matter and K value of the soil. Maximum fish production from rice-cum-fish culture system, 30-40 fishes dec^-1(7500- 10000 ha^-1) may be recommended as the best stocking density with duckweed integration. The highest fish production (521.20 kg) and net income (TK 23537.50) and the lowest fish production (320.16 kg) and net income (TK 14540.0) ha^-1 was obtained from T₃and T₁ respectively. Though stocked at a higher density, no adverse effects on the survival and growth of the stocked fishes and soil and water quality of the rice plots were observed. The result indicated that the higher stocking density with Azolla integration may be advocated to increase fish production and farmer's income from rice-fish culture in Bangladesh.

Knowledge Management: Journal