Here are some factors to consider in selecting a site for culturing fish with rice:
1. Does the family have a particular area in mind? Whatever the answer, try to visit either the specific plot or the general area with one or more family members.
2. If the family already has an area in mind, ask what the members like about the area and take these into account in considering the following points.
3. Water (most important)
The field must hold water continuously for several months; the longer, the better, for the fish. For best results, the field should be covered to a depth of about 30 cm, but if some areas are shallower or deeper than this, there is no serious problem.
Does the farmer think he can achieve this? The higher-lying the field, the less water it is likely to catch. However, dikes and field boundaries must be above maximum flood level. The lower-lying the field, the more floodprone it becomes. At what level does the farmer feel sure he can control flooding?
4. Clay will hold water better than sand. Where does the farmer feel water will stand longest?
If the field must be placed on a sandy area, generous manuring throughout the season will improve its water-holding capacity. How much manure can the farmer add?
Form a compact ball from a handful of soil and drop it half a meter to your other hand. If the ball does not break, the soil holds water well. Successful culture is possible in poor soils, but faces more limitations.
5. How close to the farmer's house or «working shelter» can the field be placed? This makes checking the ricefield and feeding the fish less time-consuming. It also helps to discourage thieves.
6. Preparing the ricefield for fish culture is a lot of work. How can the farmer take advantage of existing conditions on his land to save effort? Some examples are given below:
8. The earlier a field is transplanted, the sooner it will be ready for fish. This means the fish may have a longer growing period.
9. The farmer may want to integrate his fish culture with his livestock, vegetable garden or other operations. In such a case, the site he selects may not be best for fish, but may be good for the whole operation.
10. Will the placement of the pond cause neighbouring fields any problem?
11. Any other considerations? Ask the farmer!
Issues for further consideration
It could be considered if fish should be introduced into direct-seeded (not described above) as opposed to a transplanted rice system. This is increasingly common with labour shortages in many parts of Asia.
The management of wild (i.e. unstocked) fish vs. stocked fish may have a bearing on system design and location. In many areas, e.g. in Bangladesh, there is a strong market demand for indigenous species. There the rural poor depend on small indigenous species caught from the seasonal floodplains, but these are becoming increasingly scarce as manifested in rising prices. Attempts at their cultivation, through entrance of spawn into the ponds from open waters, or through artificial reproduction and more intensive rearing in polyculture, which is being increasingly researched, may provide opportunities for smallholder farmers and their produce may fetch higher per-kilo prices and help meet market demand.
Designs may also consider the concept of the ricefield-to-pond continuum, with opportunities, advantages and disadvantages in cultivating stocked and unstocked species.