What is Cage Culture?

By Alex Choompo

Fish are raised commercially in one of four culture settings: open ponds, raceways, tanks, or cages. Cage culture of fish utilizes existing water resources but encloses the fish in a cage or basket which allows water to pass freely between the fish and the pond.

The origins of cage culture are a little vague. It is likely that the first cages were used by fishermen as holding structures until fish could be accumulated for market. The first true cages for producing fish were seemingly developed in Southeast Asia around the end of the last century. These early cages were constructed of wood or bamboo, and the fish were fed trash fish and food scraps.

Modern cage culture in Zambia began in the Kariba Dam, with the advent of synthetic materials for cage construction. It has since extended to Lake Bangweulu and now been implemented in the lake Lusiwasi of Serenje district under the Agriculture Productivity and Market Enhancement Project APMEP.

Pond culture was more economically viable and, therefore, received most of the research focus.

Today cage culture is receiving more attention by both researchers and commercial producers. Factors such as increasing consumption of fish, some declining wild fish stocks, and a poor farm economy have produced a strong interest in fish production in cages. Many of Zambia’s small or limited resource farmers are looking for alternatives to traditional agricultural crops. Aquaculture appears to be a rapidly expanding industry and one that may offer opportunities even on a small scale. Cage culture also offers the farmer a chance to utilize existing water resources which in most cases have only limited use for other purposes.

It should be emphasized that cage culture of fish is not foolproof or simple. To the contrary, cage production can be more intensive in many ways than pond culture and should probably be considered as a commercial alternative only where open pond culture is not practical.

Considerations for cage culture

As with any production scheme cage culture of fish has advantages and disadvantages that should be considered carefully before cage production becomes the chosen method.

Advantages

Cage culture does have some distinct advantages which include:

● Many types of water resources can be used, including lakes, reservoirs, ponds, strip pits, streams and rivers which could otherwise not be harvested. (Specific state laws may restrict the use of “public waters” for fish production; check with the department of fisheries, to know the dos and don’ts, on species and levels of pollution acceptable.

● A relatively low initial investment is all that is required in an existing body of water.

● Harvesting is simplified.

•Observation and sampling of fish is simplified.

● Allows’ the use of the pond for sport fishing or the culture of other species.

These advantages are appealing. A potential fish farmer can produce fish in an existing pond without destroying its sport fishing; does not have to invest large amounts of capital for construction or equipment; and can, therefore, try fish culture without unreasonable risks.

Disadvantages

Cage culture also has some distinct disadvantages. These include:

● Feed must be nutritionally complete and kept fresh.

• Low Dissolved Oxygen Syndrome (LODOS) is an ever present problem and may require mechanical aeration.

● The incidence of disease can be high and diseases may spread rapidly.

● Vandalism or poaching is a potential problem.

The potential for loss of fish due to poor nutrition, LODOS, disease and poaching is real and shouldn't be taken lightly. Feeds must be complete and provide all the necessary proteins, carbohydrates, fats, vitamins and minerals needed for growth and health. Feeds cannot be allowed to deteriorate during storage. Low Dissolved Oxygen Syndrome may occur within a cage and not affect the fish free in the pond. Because fish in cages are crowded and confined, aeration may be more necessary for a cage system than it would be if the fish were loose in the pond. Diseases must be identified and treated rapidly. Vandalism is a problem which has to be anticipated and precautions must be taken. It should be emphasized that cages do not increase the amount of fish (i.e., pounds) that can be produced in a pond. This is particularly true in ponds with wild fish populations.

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