Through joint efforts the project, Lilongwe University, a method for intermittent harvesting was developed, based on expert discussions and literature research. The size-selective fish trap was designed for easy and regular harvest of juvenile fish in mixed-sex tilapia cultures, mitigating the risk of a total loss of fish crop due to extreme weather events. Next to the better management of the pond’s carrying capacity, the low-cost fish trap was expected to improve household nutrition and cash flow of small-scale aquaculture farmers. In a series of experiments different fish species, stock densities and time intervals for the use of the trap were tested. On-farm trials were conducted to test the innovation’s use in the field. With the application of the trap for intermittent harvest the total yields under optimal conditions were 25 percent higher than in the control group with single batch harvest. Throughout the three-month trial in the field, the farmers used the trap two to three times a week. An average of 830 g of small but marketable fish was caught each time, adding up to over 20 kg of continuous fish supply for the farmer.
This additional catch provided a steady source of food for the household or could be sold at favourable prices, especially when local market fish supplies were low during the aquaculture cycle.