Fish Projects That Simply Won't Fly

Concrete-sided ponds are unable to mimic the natural aquatic habitats found in floodplain pans, which teem with insect larvae, a superb food source for fish. Farmers therefore feed the fish exclusively on expensive fish pellets, which they cannot afford.

On a recent visit to the Barotse floodplain of the Upper Zambezi to study aquaculture in the area, I was struck by a number of aspects.

To begin with, the Zambezi River hardly flooded at all this year. Peak flood season usually occurs in April, when rains that fall earlier in the upper catchment in Angola penetrate the floodplain and the water spreads out into numerous pans and channels, with the level gradually dropping from May onwards.

The entire ecology of the fish population is tuned into this cycle of flooding and drying, with fish moving from the main channels into flooded margins to breed, and the resulting fry and fingerlings moving off the floodplain as it dries in winter. These shallow grass-filled pans are full of nutrients derived from flooded vegetation and animal manure. Fish growth is rapid, and survival high. None of this happened during the past season, which bodes ill for the future fish population of this area.