Effects of rice-fish integration on the Productivity of irrigated paddies in east Kano Irrigation scheme, western Kenya

Abstract

Rice-fish integration is practiced in many places in the world with varied success. Carps, milkfish and tilapias are traditionally used. One other potential fish, particularly for Africa, is the African catfish tClarias gariepinusi. Whereas adoption of rice-fish integration technology would potentially increase aquaculture fish production in Kenya, local trials have not adequately been undertaken resulting in knowledge gaps including number of fish species involved under integration and the yields of both fish and rice, that this study sought to bridge. The present study integrated Basmat rice variety with African Catfish (Clarias gariepinus) and Nile tilapia (Oreochromis niloticus) at Ahero Rice Research Station in Western Kenya (.0°08' Sand 34°56' E) with a view to assessing the viability of such integration in Western Kenya. Three treatments with varying fish stocking densities were tested in triplicate - rice-catfish low density (4 fish/m"), rice-catfish high density (8 fish/m") and rice-catfish-tilapia polyculture (4 fish/m ' per species). The paddies were fertilized but no suppiementary feeding was done to the fish in all the treatments. After a 122days ' trial, the mean weight of catfish had increased from the initial weight of 16.6±0.2g to 136±11.2g in RCH, 16.0±0.lg to ISO.3±6.4g in RCL and 16.2±0.4g to IS6.9±9.09g in RCT. For tilapia mean weight had increased from the initial of 10.0±0.lg to IOS.4±7.0Sg. The catfish yields were 373.16 kg/ha in the RCT, 288.88 kg/ha in RCH and 236.26 kg/ha in RCL. Catfish grown under RCL recorded lowest growth rates, which was significantly different (ANOY A; p<O.OS) from the other treatments. Rice yield over the same period was 33S0 kg/Ha in RCT, 2898 KglHa in RCL and 2696 KglHa in RCT. Both yield of catfish and rice were significantly higher (ANOY A; p<O.OS) in RCT compared to RCH and RCL. The differences observed between the different treatments with respect to the environmental parameters were however not significant (ANOY A, P > O.OS). This study demonstrated highest productivity with rice-fish polyculture integration, giving highest yields for both the fish species - catfish and tilapia, and rice. Although carried out in a new environment, these findings showed potential for success and are suggested for up-scaling and adoption in East Kano. The impact of giving supplementary feeds to fish in a rice-fish polyculture integrated system is recommended for further investigation.