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close this bookWorkshop to Produce an Information Kit on Farmer-proven. Integrated Agriculture-aquaculture Technologies (IIRR, 1992, 119 p.)
close this folderEconomic, sociocultural and environmental considerations in introducing integrated agriculture-aquaculture technology
View the documentSociocultural considerations when introducing a new integrated agriculture - aquaculture technology
View the documentEconomic considerations in introducing integrated agriculture-aquaculture technologies
View the documentWorking with new entrants to integrated agriculture -aquaculture
View the documentIntegrated agriculture-aquaculture and the environment

Sociocultural considerations when introducing a new integrated agriculture - aquaculture technology

It is important to understand how farmers understand the world before trying to introduce new technological options. Try to discover whether or not the new system can fit in well with the farmer's concerns, beliefs and values. And remember, farmers are "scientists", too. They have been developing, testing and adopting their own technologies for centuries in ways that are tailored to their cultural setting. If you make the effort to learn from them about the fit between cultural outlook and technology first, you will have a much better idea of which new technologies they are likely to take an interest in.


1. Even science is "cultural" — It is a belief system that incorporates certain values and goals and promotes a particular view of the world.

Even science is "cultural “

Agricultural scientists and economists value precision in measurement and the replicability of results, as well as maximizing efficiency and profitability.

Farmers may be motivated by goals and values that are different from those of scientists and economists.

Farmers may value security of livelihood for themselves and their children in the short and long term; they might place a higher priority on preserving harmony in the community than on maximizing individual gain; or they may seek to acquire merit for the afterlife, by contributing fish to a temple rather than selling them for money.

2. Cultural rules often limit what particular members of a given society (e.g., women versus men) can do. Cultural factors may determine who usually makes decisions, who is allowed to work in the fields, who may go to town to market produce and who may travel to a research station to attend demonstrations. This may set limits on the flexibility of households and communities to adopt new technologies. For example:

Cultural rules often limit

Women may not be permitted to catch fish, but they may be the ones who sell them.

Considerations of gender, religious beliefs, caste or clan membership, all may limit the distribution of benefits to be derived from farming innovations.

3. Interactions between extension agents or institutions and farmers may be constrained by culture.

It may be unacceptable for male extension workers to speak freely with women. Or a young extension worker may feel uncomfortable giving instructions to a distinguished community elder.

4. Culture changes over time: Children often have different beliefs, attitudes and values than their parents. This can cause conflicts over resource use priorities. For example:

Children may aspire to enter non-farm occupations; or they may be less concerned with respecting religious taboos.

Children may aspire to enter non-farm occupations

5. Communities and consumption. Farming communities are often divided by factors such as religion, caste, economic class and political affiliation. A given technology may not be suitable for the whole community and may increase conflict within, it.

Communities and consumption


There is no reason to encourage people to raise fish if they will not eat the fish themselves and if they cannot find anyone who will buy the fish. The same is true for any livestock or vegetable product that may be part of an integrated farming technology. It is, therefore, essential to consider the local cultural and economic constraints on consumption before attempting to introduce such a new technology.

Cultural constraints on consumption may include:

1. Religious Bellefs

For example:

- Muslims will not eat pig meat; many will not consume shell fish, but this depends on local custom and preferences.

- Most Hindus will refuse cow-meat; some castes eat no meat, fish or livestock product of any kind. Again, this will vary from region to region.

- Some Buddhists will no. kill and consume domesticated animals (including farmed fish) even though they will eat wild fish.

2. Totemic Beliefs

- Especially in Africa, but also among tribal peoples in Asia, Melanesia and the Americas, some people are forbidden to eat the animal that stands for their clan group.

3. Beliefs about Gender Differences

- In some societies, men may be allowed to eat certain foods that are forbidden to women and vice versa. Often, men expect to be given the most nutritious and preferred foods first. These factors may reduce the nutritional benefits that women receive from fish or livestock product/on. On the other hand, sometimes women can demand these foods when they are pregnant or nursing.

4. Beliefs about Food Cleanliness and Health

- Sometimes people believe that certain foods are unclean or will make them sick. For example, many people refuse to eat fish raised on animal excrete for these reasons.

Here is a checklist to help you think about how cultural beliefs might affect the adoption of the new technology you want to introduce. What other technology might be more culturally appropriate?

Consumption checklist

Will be available and acceptable to:






Pig Meat

Cow Meat

Poultry Meat

Eggs/ Filk









Local Markets

Distant Markets

This checklist is just to help you decide whether or not a new technology will generate products that are going to be available and acceptable to all members of the producing households as well as to buyers in the market. You must still, however, make a separate assessment of the long-term level of demand and prices in the markets that he produces might be selling to, (and purchasing inputs from), before deciding whether or not a given technology will be viable. See the paper on Economics Considerations In Introducing Integrated Agriculture-Aquaculture Technology.


In most farming communities, women and men do different kinds of tasks on and off the farm and in the house. A new integrated farming system technology will usually require changes in the way that members of the farming household use their time. Some might have a greater burden of work (e.g., feeding fish or livestock, repairing dikes, selling fish) and need to reduce the time they spend on other activities. But this is not always true. Sometimes, new tasks can be easily combined with present activities (e.g., digging a trench can supply fertilizer for horticultural crops on an embankment) or children and elders can perform new tasks that are not physically demanding but costly in terms of time (e.g. feeding fish in a distant pond).


The following checklist will help you to think about these problems and whether or not they can be easily solved by the farming household. But remember, households differ. Some have lots of young children who require supervision. Sometimes, an elderly widow will be living alone and doing most things by herself because her children have gone to find jobs in town. How can an integrated system help someone like her to increase her food and income without demanding more labor time? Are there neighbors, relatives or a women's group with whom she can cooperate and get help?

For each task on the checklist, make a mark under "Present" if the category of family member (children, adult women, adult men, elders) contributes substantial labor under the existing system. Then make a mark under "Future" if they will need to contribute once the newly integrated system is adopted.


adult women

adult men










Field Labor

- Field

- Preparation

- Pesticide &


- Weeding

- Harvesting



- Grain

- Livestock

- Fish



- Feeding

- Milking,



- Eggs

- Pen Maintenance

- Herding


- Cooking/Cleaning

- Building/Maintenance

Child Care

Tool Making/Repair

Marketing Produce/

Buying Inputs

Working for Wages

Other (Trading,

Crafts, etc.)


Before introducing a new integrated agriculture-aquaculture technology, it is important to consider who will make the management decisions that are crucial for its success. For example, elders might have ultimate authority in the household concerning when to sell crops or livestock, but make few day-to-day management decisions concerning stocking rates, feeding and fertilizing.

Women often manage family finances as well as making day-lo-day decisions concerning food purchases and preparation. Because women are usually responsible for ensuring adequate nutrition for themselves and their children, they are often more motivated than men to adopt new technologies that provide nutritional benefits, such as fish culture. Also, women will be eager to invest their time in improving the productivity of a resource over which they have control of both management and the harvested product (for example, a backyard pond).

Distribution of resources

When we speak of "distribution", we mean the ways in which the resources needed for an integrated farming technology are made available to farmers. Some resources will be available on the term and cost nothing (if the farm household owns them). These resources may have to be diverted from other Uses, however, and this constitutes a hidden cost. Other resources will have to be borrowed, leased or purchased.

Before attempting to implement any of the technologies in this Kit, you should try to answer the following questions together with the farmers you are working with. (You can do this as part of the drawing exercise discussed in the selection on Working with New Entrants to Integrated Aquaculture-Agriculture.

1. What resources are easily available on most farms in the area? (A new system should not depend upon resources that are scarce, difficult or expensive to obtain.)

2. Which of these resources is being under utilized/not utilized? (A new system should focus on bringing these into the system).

3. Which of these resources is being over utilized/not being utilized in a sustainable fashion? (A new system should strive toward restoring sustainability.)

4. Which of these resources is a common property resource? (A common property resource is a resource that is jointly drawn upon and managed by a community or a part of a community, e.g., grazing lands, ponds, irrigation water, forest products. A new system should enhance the benefits all users receive from such resources).

5. Which of these resources are controlled by only a small percentage of farmers or by non-fammers? (Farmers will be reluctant to invest in a system that requires resources that are not under their ownership or control, such as land that might be sold or an irrigation water supply that might be cut off someday.

On-farm resource availability and utilization checklist


Under utilized

Must be Diverted

Common Property


Over utilized Distributed

a. LAND (Proper soil slop, drainage)

b. WATER SOURCE (Reliable, sufficient quality)



e. HOUSEHOLD WASTES(Ash, Sewage, Food wastes)






k. LABOUR (Knowledge/skills, numbers, strength, timely availability)


It is useful to remember that most farmers in the world have little margin for taking risks. Sometimes, building a store of value to provide insurance against catastrophes (such as drought, flood, political upheaval, market instability, social and legal obligations) may be perceived by the farmer to be more desirable than investing for maximum returns.

Farmers view their ties with friends, neighbors and kinfolk as insurance against risk as well, since they will rely on these people for help if disaster strikes. This is why farmers invest in social relationships—by sharing resources (such as money, tools and labor), by paying visits, attending community celebrations and religious ceremonies and by exchanging gifts. It a farmer harvests fish or poultry before they are mature, it may be because he or she must meet a social obligation that can't be put off until later. Farmers should not be expected to make decisions in accordance with fixed models. Rather, the models for integrated technologies should be flexible enough to accommodate farmers' varying needs and their perceptions of acceptable risk.

Most farm households will be familiar with the benefits that may be derived from integration in terms of reducing risk. Most likely, they already combine diverse enterprises (e.g., livestock, crops, wage labor, gardening) in order to protect themselves from the possible failure of any single endeavour. The integration of agricultural enterprises with fish culture can increase household security by providing additional sources of income, by improving cash-flows over time and by improving the long-term sustainability of the household and community resource base. Also, when nutrition is improved through integration, people become less vulnerable to illness.


The farming households in any community are likely to have unequal access to resources and unequal control over their use. Often, extension agents focus on "leading farmers" or "progressive farmers" — those with the greatest access to resources on the farm or with sufficient income to purchase these resources off the farm. Extension agents do this because it is easier to show a complete, complex system on a single farm or because these farmers often have more education and are more likely to "think like" the extension agent. These farms are often used to "demonstrate" the gains to be achieved from an integrated system. However, there are good reasons not to focus on resource-rich farmers. in technology extension efforts.

Inequality between households

· Resource-poor farmers will usually be discouraged from adopting a new technology they are shown on a wealthier farmer's farm. (They will think, "how can I possibly do it without land and cash?).

· Resource-rich farmers often control the distribution of inputs to poor farmers. Helping the rich farmers to expand may reduce access to resources by poor farmers, making it yet more difficult for them to adopt a new system that may improve their livelihood.

· When resource-poor farmers lose access to the means of survival, they are pressured to use the most fragile parts of the local ecosystem in order to gain a livelihood, often leading to environmental degradation. New technologies should be focused on solving this predicament; they should enable farming communities to manage environmental resources in a sustainable fashion by improving the security of livelihood for the community's poorest members.

· Remember, farmers continue to live in communities after outside advisers leave. This is why it is a good idea to use extension agents who have intimate knowledge of the community they serve and why it is good to involve the whole community in choosing new and locally appropriate systems. If one farmer shows a rapid increase in visible wealth after adopting a new technology, others may be envious and isolate them from the community or sabotage their investments.

Integration can reduce inequality in communities if the primary beneficiaries are the resource-poor community members.

· By making the resources they have access to more productive, poor farmers become less dependent on loans or favors from wealthy farmers.

· Involving resource-poor farmers in designing new integrated technologies may be a way of strengthening their control over their own lives and giving them better organizational capacity and power in the community.

Prepared by: ERIC WORBY


Economic considerations in introducing integrated agriculture-aquaculture technologies

The importance of economic analysis


FIRST, make a costs sheet.

· List the things that are required for you to use the technology.
· Write down how much is needed, its price and the amount paid.
· Add all amounts paid to find out the total costs.

Costs sheet

SECOND, make an income sheet.

· List all the products from the technology that were sold.
· Write down how much is sold, at what price and the amount received.
· Add all amounts received to find out the total income.

Income sheet

THIRD, work your Affiance or profit sheet.

· Write down the total income received from the technology.

· Write down the total costs that were required in doing the technology.

· Subtract the total amount paid for you to use the technology from the total amount received from the sales of the technology.



Cash Outflow

· Work out your cash outflows.. Note down the activities of the technology that required money and write these on the lower pare of the calendar. Also, write down the costs involved.

· Under January, the first month of the technology, record plowing and harrowing where hired laborers were paid P320 for four days. Record also the purchase of rice seeds which cost P620.

· For the second month of the technology, record transplanting activities which required P160 as wages for hired laborers. Also, record the purchases and money paid for fingerlings, rice bran and Inorganic fertilizer.

· Repeat recording on the calendar the activities of the technology that I money and the amount paid for the

Cash Inflow

· Work out your cash inflows. Note down the products sold and the money received from these sales and write these on the upper pan of the calendar.

· In April, the fourth month of the technology, 25 knot fish were sold for P875.

· In May, 3,000 kg of rice were sold for P12,000 and 100 kg of fish for P3,500.

· Smaller size fish were kept in the pond for further grout. A total fish harvest was done in June and 25 kg of fish were sold getting P875 in receipts.


Cash Netflow

· The previous illustration of activities of the technology and the cash flows can be summarized by: 1) adding all money required to do the technology in particular month to get the total monthly cash outflow; and, 2) adding all the money received from the sales of the product of the technology in a particular month to get the total monthly cash inflow.

· Draw another calendar showing each month included in the previous calendar.
· Pat the total cash outflow by month on the lower part of the calendar.
· Pat the total cash inflow by month on the upper part of the calendar.
· The cash netflow is computed by subtracting the cash outflow from the cash inflow.

· A negative cash netflow, particularly the case in the first few months of the technology, means that the farmer spends money to buy and pay for things that are required by the technology. If he starts getting cash inflows, a negative cash netflow implies that more cash is required to pay for the technology than what is received from the sales of his products.

Cash netflow

· A positive cash netflow implies that the farmer receives money from the sales of the products of the technology. When there are cash inflows and cash outflows in a particular month, a positive cash netflow means that the farmer receives more cash from the sales of his farm products which are able to pay for the tame expenses at that particular month.


· The farmer may have several alternatives in using his resources such as labor, land or cash capital as shown in the following diagrams.

· Before adopting a new technology (for example, rice-fish farming), the farmer would like to know whether using his resources for rice-fish farming would give him better income than investing these in other alternative income-generating activities.

· When the farmer has alternative uses for his resources, he should choose the activities that will generate more income from using his resources.

Farmers labor resource

Farmers land resource

Farmers cash capital resource


· The opportunity cost of a resource (for example, labor, land or cash capital) is the value of the best alternative use of that particular resource. A new technology is worth adopting if the income earned from the use of the farmer's resources are greater than the opportunity costs (or what could have been earned) in other activities.

Additional labor hours spent by the farmer's wife and children for rice fish farming

Farmers wife spends more time in the farm: feeding the fish with rice bran and cleaning the dikes instead of cooking at home for the family. Children also help in the farm chores, thus spends less time studying school lessons.


· Is the produce from the technology meant for household and local consumptions or for export?

· How diversified will the farm operations become when the new component technology is adopted? Will it increase/reduce risks in crop failure?

· Will the products of new technology be subjected to high degree of price uncertainty because of unstable market? How sensitive is the net return to changes in input costs and output vices?


· Is it going to place significant demand for labor time from family members? Who will meet such labor demand? What is the opportunity cost of additional labor hours in terms of leisure, children's schooling, household work by female labor force, etc.?


Heavy insect/disease damage to the rice crop will result to poor yields. Income from rice may not even be enough to recover farm expenses. However, as the fishes are kept safe in the pond refuge, sales from fish relieve this situation.

Heavy insect/disease damage to the rice crop



Working with new entrants to integrated agriculture -aquaculture

Developing integrated aquaculture-agriculture systems for small holder farmers requires their participation. Farmer involvement is crucial because farmers are the ultimate designers and managers of farming systems.

Often, small holder farms are highly complex mixtures of crops, trees and livestock which vary seasonally, using a range of resources and cultivated ecosystems.

With such a diverse and difficult set of conditions, field extension workers are often confused as to where and how to start.

One possibility is to utilize a very simple farmer-to-farmer technique that enables farmers to draw models of their farms with the help of other farmers and extensionists. The importance of this exercise is that farmers learn by doing.

The objective of farmers' drawings is to use this medium as a means for farmers to visualize their farm system so that they are better able to see new possibilities for integrating farm enterprises. These could be integrating new enterprises into the farm system or creating new linkages between existing ones.

Hopefully, there can be follow-up drawings with farmers to see how their farm systems evolve as they adopt new integrations.


The most appropriate setting for this exercise is in the farmer's own environment on the smaliholding or in the village. Usually, it is better to start with groups rather than individual farmers.

Not only do groups allow more people to participate but also provide better dynamics than individual interactions when trying to make new entrants aware of different types of farm integration.

Group composition is also important. Mixed groups which include women, men and children often work very well. However, the facilitator needs to ensure that individual interests do not dominate the gathering. In this context, it may be useful to have follow up visits with single gender groups to see if viewpoints differ. You may choose to target groups of farmers who are likely to benefit from certain forms of integration. Rice farmers would be a suitable group for discussing rice-fish integration, for example:

· Cordially greet your farmer group and introduce yourself to everyone in the manner appropriate for the cultural setting.

· Explain that you have come to learn and understand how the farmers traditionally manage their farms

Cordially and explain your farmer group

· Suggest that they take you for a walk around the village or farm so that you can better understand their agricultural setting. Walking around and chatting in a relaxed atmosphere allows farmers time to relate their experiences. Thus, social distance and communication barriers are reduced. Do not take notes during this walk, just listen.

Suggest that they take you for a walk around the village

· Once the walk is over, continue the discussion. At an appropriate time, explain that with so much information, you find it difficult to visualize the whole farm system. Suggest to them that it would be easier for you to understand their farms if they could be represented in a drawing.

· If the farmers are agreeable to this idea, then explain carefully how to proceed with a drawing. Describe how actual plant or animal material can be placed on the ground to symbolize individual enterprises.

Explain carefully how to proceed with a drawing

· Once farmers grasp this idea, then introduce the idea of linkages between enterprises with arrows. These arrows can be scratched out on the ground with a stick or marked with ash from fires. By doing this exercise for themselves, farmers learn more quickly the possibilities for integration on their farms.

Introduce the idea of linkages

· Farmers should be allowed to interact among themselves so they can exchange ideas and produce a picture through joint effort. This group effort enables farmers to quickly learn from each other a range of ways of integrating farm enterprises.

Individual enterprises

Farmers should be allowed to interact

If several farmers draw their farm systems together—drawing becomes a valuable tool for exchange of ideas between peers.

Interchange of ideas facilitates generation of new ideas among farmers.

· The final drawing should show the full range of enterprises on the farm and linkages between them.

This conveys farm integration more effectively than either written or spoken word.

A picture of the farm system helps farmers appreciate their own farm as an integrated unit of interlinked enterprises

· Finally, the farmers should be encouraged to consider how new linkages, inputs (on-farm and off-farm) and enterprises might be included on the drawing.

Once a picture is drawn, it is easier for farmer/researcher/extensionist to see the possibility of making new links.

If a new enterprise is being introduced, it can be added to the drawing—so the picture becomes the medium through which to discuss possible effects on farm operations.

Drawings of individual farms enables the extensionist to see how integration varies from farm to farm.

· Drawing on a regular basis enables extensionists and farmers to follow through in a stepwise fashion the evolution of integration.

If farmers expand their drawing to include the whole village area, then common property resources can also be identified which have potential for linking to farm enterprises such as aquaculture, livestock, etc.


Incorporation of new enterprises, such as forestry and aquaculture, requires careful integration into traditional farming systems so that food security and income are not disrupted.

By drawing farm systems, farmers are better able to understand how new enterprises can be slotted in and enhance production of current enterprises with minimum disruption.

Farmers can also evolve new integrations and management systems for themselves when they visualize their whole farm in a drawing.

Farm diagrams

Farm diagrams can also provide information on labour allocation with regard to gender. In the diagram above, simple symbols (women, men) indicate whether men or women or both are moving resources around.


· Do not arrive on the farm at a bad time. One should check that farmers can receive you at the times you propose. This is particularly important where one wants to include mixed gender groups where women have different daily routines to men.

· Do not arrive on the farm with a large number of colleagues. This not only intimidates the farmers but also denies you the value of arranging your interview so that you empower women and other -disadvantaged groups to speak out. More knowledge and experience are gained where a few interview many.

· Do not arrive on the farm in city clothes and giving orders. This only serves to increase the distance between you and the farmers. Your attire and attitude are powerful signals to rural folk; what they say is largely determined by how close you can get to them.

· Do not rush the interview. This usually results in you reconfirming what you already know because the unhurried exploration for new insights and cross-checking has not been possible. Relax, listen more than you talk and show respect of their knowledge by following up on leads offered by the farmers.

· Do not force your agenda. Our overriding concern to get the output needed and conclude the interview quickly reduces the quality of our data and our relationship with the household. Rather, we should let the information emerge naturally. Forcing farmers to draw diagrams not only results in you drawing the diagram for them, but also in the farmers finding little value in them. This makes it difficult for you to return. If farmers learn from the interview, they will invite you back.

· Do not continue on with a bad interview. When, for any number of reasons, you find yourself interviewing farmers who are distracted by other matters, as happens to us all, recognize the fact and tactfully withdraw. It is better for you and others that follow you to have good relationships with the community rather than good data on the community.

· Do not appear with paper and pens and instruct them to draw a picture of their farms. This will not work. The picture must emerge naturally as a way for the farmers to express all that is happening on their farms.

· Explain to the farmers that they are the teachers in this exercise and you, the extension worker, are the pupil. This shows respect for the farmer's knowledge and provides a more equitable working relationship between the visitor and farmer.

· It is important to encourage farmers to use their own methods and materials to represent farm enterprises. The visitor should avoid doing any drawing; otherwise, the farmers might be intimidated and withdrawn.



Integrated agriculture-aquaculture and the environment


Food production invariably has environmental effects: occupation and fragmentation of former natural habitats; reduction of the abundance of diversity of wildlife; and, changes in soil water and landscape quality. Most integrated agriculture-aquaculture systems use low levels of inputs and fall within the type of aquaculture called semi-intensive. This means less reliance on heavy feed and fertilized inputs, lower densities of farmed organisms and, therefore, less chances of causing serious pollution and disease risks than more intensive, feedlot-type systems. This is important as it is the high output of the foodstuffs necessary for intensive feedlot systems that create environmental pollution. Semi-intensive systems in synergy with agriculture (crop-livestock-fish integrated farming) capitalize on in situ, vitamin and protein rich natural aquatic feeds, which obviate the need for expensive feed components.

Semi-intensive freshwater ponds usually have few environmental effects other than their occupation of former natural habitats. In the tropics, where there is fast turnover of organic waste loading, their effluents and excavated muds usually enhance the productivity of adjacent waters and lands and avoid over enrichment.

Special care is needed, however, where pond and dike construction may disturb acid sulfate subsoils and where water table changes may uplift subsurface salts. Moreover, saltwater intrusion from coastal ponds may poison soils and freshwater aquifers. The use of chemicals in semi-intensive aquaculture is usually limited, but farmers should always take great care when using antibiotics, hormones and other drugs and should follow the instructions very closely. Seek professional advice from veterinarians or fish culture specialist and be aware that many drugs are persistent in the environment.


The aquatic medium is shared by many users and supports diverse fauna and flora. As aquaculturists develop better domesticated breeds, international demand for these will increase. This means increased transfers of exotic breeds, as has been of immense benefit for crop and livestock farming. However, cultured aquatic organisms often escape and form feral populations which may: (1) displace or interbreed with wild stocks, thereby threatening natural genetic resources; (2) disrupt natural habitats by causing proliferation or clearance of vegetation or increasing turbidity (benthic foraging); and, (3) introduce aquatic pathogens, predators and bests inadvertently.

Development agencies and farmers must weigh the benefits of using exotic breeds against possible environmental consequences. Development projects and farmers often try exotic breeds without thorough appraisal of the possible consequences. Such irresponsible experiments may have far-reaching consequences; loss or damage to habitats and genetic resources of wide importance. This damage may last forever. Codas of practice to avoid this have recently been developed, but aquaculture development still lags behind agriculture in recognition of the risks of transfers and international application of these safeguards.

The only general guidelines here are: (1) use native species and breeds developed by local or national programs wherever possible; and, (2) if the introduction of other species or breeds need to be considered, seek professional advice on how to assess the possible consequences and comply with the laws and Codes of Practice that have been developed for the good of all present and future farmers.


Integrated agriculture-aquaculture generally has no special health risks significantly greater than agriculture, but freshwater ponds may assist the spread of waterborne diseases. They can harbor the intermediate hosts of parasitic worms, such as bilharzia, and can be breeding sites for mosquitoes. Such problems are minimized by maintaining weed-free, well-stocked ponds. In fact, many species of fish eat and control mosquito larvaes but snail control by fish is not usually possible.

Fish farm workers who enter ponds may risk bilharzia infection in infected areas and other waterborne microbial diseases (viral, leptospiral, bacterial and fungal).

On the positive side, many of the pathogens and parasites that contaminate fish produce from livestock excrete-fed ponds are eliminated by a well-fertilized pond environment, as in sewage oxidation ponds. Problems of pesticide accumulation in ricefield fish are diminishing because of the increased use of integrated pest management programs employing natural substances and predators.

The risk of accumulation of heavy metals from livestock feeds in manured pond sediments and fish is slight and applies more to intensive systems. The same probably applies to pathways for aflatoxins (poisons that develop from fungi in badly stored feeds) but this has been little studied.

Sewage-fish culture is controversial because of assumed health risks to farm workers and fish consumers. However, these may be slight compared to the nutritional benefits provided that postharvest handling of the fish is hygienic (with particular attention to not rupturing the gut and allowing its contents to make contact with fish flesh). Such produce must also be well-cooked.

There are no general guidelines on how to minimize these risks other than to be aware of which waterborne diseases are present in any given locality and to assess whether the establishment and operation of ponds significantly adds to the risks of contraction by farm workers, fish handlers and consumers.

Seek professional advice from public health workers.

Prepared by: ROGER PULLIN