Review paper on the production trials of rice-cum fish culture - a transferable concept into Niger State, Nigeria

This paper reviews the production trials of rice-cum-fish culture. Rice and various fish species using rotation and concurrent methods of cultivation are used. The farming system is mostly practiced and researched in to in Southeast Asian countries. It addresses the problems of high external inputs, sustainable aquaculture, poverty and nutrition in the rural population, insect pests, use of insecticides, weeds control and under-utilization of agricultural lands. The production trials yields are summarized and a summary of annual income per hectare from rice and fish have been given. The yield however depends to a large extent on the species stocked, culture period, fertility of the soil and water, degree of supplemental feeding and culturing methods. The production results are discussed. Niger state is blessed with abundant wetlands/rice fields suitable for the practice. However, ecological differences from country to country and region to region, research and development trials are necessary to ensure a successful adoption of the technology to farmers in the State

Environmental impact assessment of agrochemicals for fish production - a review paper

The environmental impact of agro-chemicals for fish production was extensively reviewed. The positive contribution of agro- chemicals and the devastating effect on aquaculture was x-rayed to alert users to this obvious environmental problem. Lime and fertilizers are commonly used in fish farming to increase pH of pond soil and water and to increase alkalinity and hardness, reduce humic acid content and to initiate primary and secondary productivity. Devastating effect of lime on environment is likely to be minimal. In the case of fertilizers, over utilization of this agro-chemical could impair water quality as phytoplankton bloom become excessive which consequently raises BOD. The use of Therapeutants in aquaculture was discovered to be more popular in Europe and North America than in the tropics (Africa). Commonly used therapeutants include antibiotics and antimicrobials. For fish pathology chemicals like formalin, potassium permanganate, Dipterex and malachite green are widely in use. Effluent from farms where these chemicals are commonly in use can distort the aquatic ecosystem. The changes in water quality, aquatic community structure and productivity caused by intensive aquaculture are typical of the impacts of pollution from a wide variety of sources like sewage, agricultural run-off and effluent discharges from industry

Aspects of ecology of Owena reservoirs: implication on fish production

The article gives physical description of Owana reservoir, Nigeria. The reservoir was chemically and thermally stratified partial mixing of the water was observed during the rains. The concentration of major ions in the water showed distinct peculiarities. The captions (Na super(+), K super(+)Ca super(H),Ca super(Z), Mg super(++)) SO sub(4) super(2-) were relatively low. The water had high dissolved oxygen, it was acidic and also had low values of alkalinity, conductivity and total dissolved solids. About 61 plankton taxa belonging to 21 species were identified. The reservoir supports a commercial fishery of about fifteen fishermen with about fifteen species of fish caught daily with the aid of traps set and cast nets. Effective management of the lake will enhance fish production