This is the VOA Special English Agriculture Report.

A listener in Abuja, Nigeria, named Okorie wants to know more about fish pond farming.

Bill Martin, president of Blue Ridge Aquaculture, with tanks of shrimp in Martinsville, Virginia

Raising fish in ponds of standing water can work well on a traditional farm. Animal and crop waste can be used to fertilize the pond and feed the fish. And mud from the bottom of the pond can be used to fertilize the crops. Also, water for the farm can be stored in the pond with the fish.

Experts say ponds with a surface area smaller than one hundred square meters may not be profitable. But those larger than one hectare may cost too much and be difficult to manage.

Pond farming is one kind of aquaculture. Other fish farms are connected to sources of free-flowing water -- a lake, river or ocean. This way you may not have to feed the fish. They can eat weeds and small organisms, like plankton and algae. Fish can also be raised in tanks, either indoors or outdoors.

Deciding which kind of fish to raise depends on the water quality, salt content and temperature. The best idea, experts say, is to raise fish that normally live in the source of water that you use. Also, you should remove wild fish, or else they could eat your fish.

Common carp are a popular choice for a fish farm. You could also raise tilapia, catfish, grouper, milkfish, eel or other kinds, depending on where you live. Some fish are harvested once a year; other kinds can be harvested throughout the year.

Biologist Martin Schreibman hopes more people will raise their own fish. He started the Aquatic Research and Environmental Assessment Center at Brooklyn College in New York. He says setting up a fish farm is easier, less costly and more profitable than people might think.

Intensive fishing has reduced populations of wild fish. The aquaculture industry now provides almost half the fish eaten worldwide. Fish farming is seen as an important way to help feed a growing world. But fish farms also require attention to environmental and food safety considerations.

The United Nations Food and Agriculture Organization released a State of World Aquaculture report at a meeting in New Delhi two years ago. At that meeting, delegates agreed on the need for more support for aquaculture development in Africa. The F.A.O. said Africa was the only area of the world where in recent years people have been eating less fish instead of more.

And that's the VOA Special English Agriculture Report, written by Jerilyn Watson. I'm Jim Tedder.