Rice-fish farming: a sustainable, innovative and efficient agroecological model in the highlands of Madagascar[La rizipisciculture : un modèle agroécologique durable, innovant et efficient sur les Hautes-Terres de Madagascar]

Rice-fish farming is both a sustainable agro-ecological model and an efficient form of agriculture-livestock integration. On the same area of rice field, fish production is added to rice production, with an increase in rice yield of around 10 to 20%. Rice-fish farming contributes to food and nutritional security and to the fight against poverty, as it is an income-generating activity. As rice is the staple food in Madagascar, Malagasy rice-fish growers are first and foremost rice growers. They give more importance to rice cultivation than to fish farming. The aim of this research is to determine the most efficient surface area of refuge canals required for the survival of common carp. An experiment was carried out in 6 elementary plots belonging to a farmer in Tsiafahy-Antananarivo, using a block design with 3 replications. The experiment compared the efficiency of the "FAO model" refuge canal, corresponding to 10% of the plot surface, with refuge holes 2 m in diameter and 50 cm deep, occupying 2% of the cultivable surface. The results showed that the improvement in rice yield largely compensated for the 10% of surface area used for the fish refuge channel. The yields corresponding to the samples gave an average yield of 1.47 ± 0.28 t/ha, which was consistent with the overall harvest of 1.44 t/ha (525 kg on 3638 m²). The two treatments with 10% refuge channels or 2% holes gave exactly the same yields, 1.47 ± 0.32 t/ha and 1.47 ± 0.27 t/ha respectively. However, the difference in cultivable area, given the area lost to refuge in the two treatments (10 or 2%), provided a delta of 11 kg in production (i.e. 2% of total production; 256 kg on 1752 m² for the plot with refuge channel and 267100 kg on 1886 m² for the plot with refuge holes). As there is no significant difference between the two treatments, the FAO refuge channel model of 10% can be reduced to 2% of total surface area. These results represent a major step forward for the development of rice-piscicuture among Malagasy rice-pisciculturists.