Photo credit: Marx Perfecto C. Garcia (Philippines) Description: Marx Perfecto C. Garcia and Abdel Rahman El Gamal (Founder of the website)
As established, the turbidity caused by eutrophication and phytoplankton bloom in fish pond is a dangerous incidence that may ultimately cause stress and even kill of stocked fish. Means for the control of the plankton bloom varied through management practices or use of chemicals. The inserted picture shows the application of chlorine dioxide in a fish pond in China. In this particular application, an amount of 500-g of chlorine dioxide powder is mixed in the boat container with about 50 to 80 L of water. The solution is broadcasted throughout the pond areas using a boat. The solution is sufficient for a pond area of about 3,000 to 4,000 m2.
The use of chlorine dioxide for such purpose is based on the ability of the compound to readily dissolve in water and so its effectiveness in the control of algae. In addition, the safety of using chlorine dioxide has been endorsed by international organizations related to food and environmental safety including the Environmental Protection Agency (EPA) and other organizations as well. Interestingly, the US Food and Drug Administration (FDA) permitted the use of chlorine dioxide as a food additive for human consumption.
While the primary use of the chlorine dioxide is for bleaching of wood pulp, it is also used for the bleaching of cereal flours and for the disinfection of municipal drinking water. The product has been registered for the use as a disinfectant and sanitiser in animal farms, food-processing and storage plants. Its use as an antimicrobial agent has been adapted in the water of poultry processing as well as in water used to wash fruits and vegetables, and for rinsing food processing equipment. A unique application of chlorine dioxide occurred in 2001, when used to decontaminate a number of public buildings following the release of anthrax spores in the United States.
Precaution: A rule of thumb if any algicide is applied to a fish pond in the existence of fish, aeration should be performed to pond water to prevent the risk of fish suffocation due to the lowering of dissolved oxygen caused by algae kill. As expected, the risk of oxygen decline will be influenced by the dense of plankton bloom and the level of algal kill. In situations, when the effective aeration is not possible, it is advised to find out other means for controlling dense algae rather than using chemical algaecide. On the other hand, in situations where algaecides is applied prior to fish stocking, all what is needed is to monitor the level of dissolved oxygen and fish stocking takes place once oxygen is back to normal after algicide treatment.