Based on your request for an "aqua fumigator", I believe you are looking for an aquarium air pump. The SB-2800 Aquarium 1-NOZZLE Oxygen Air Pump for R249 would be an excellent choice to oxygenate the water and keep your fish healthy. It comes with an air stone diffuser nozzle to break up the air bubbles for maximum dissolved oxygen without disturbing sand or gravel. Alternatively, if you need something portable, the Sobo SB-960 Portable Battery Aquarium Air Pump for R125 runs off batteries so you can use it anywhere. Both pumps come from trusted brands and have affordable prices. Let me know if you need any other details on setting up an aerated aquarium environment for your fish friends!
Based on your question about a water activated fumigator, the Insect Fogger Spray - 350ML Pack Of 10 for R612 seems like a good option. These foggers are activated by water and spray an insecticide mist or fog that is designed to control flying and crawling insects indoors. A pack of 10 gives you plenty to tackle any pest problems you may have. Let me know if you need any other details!