Establish a Mathematical Model for Key Nutrients in Catfish Ponds

Abstract

Catfish (Pangasius) is a famous and popular food in many countries around the world, and it has contributed greatly to the economy through exports. However, Pangasius farming without planning leads the fish to be more susceptible to disease and causing high pollution to the environment. The objective of this study is to use the mathematic model to identify the development processes of key nutrients in the catfish ponds. The model was used data from Washington lake and calibration and validation by measured data at the Vietnamese pond. The results showed that the actual PO₄^3- was in the range of 0.043 - 3.07 mg/l, PO₄^3- modeling in range of 0.043 to 1.956 mg/L; TP actual: 0.098 – 3.924 mg/L, TP modeling: 0.098 – 2.658 mg/L with an average error of the PO₄^3- and TP at the modeling graphs were 40% and 30.83%. The actual NO₃^- concentration: 0.018 - 0.8, modeling NO₃^-: 0.018 - 0.832 mg/L; actual NH₄⁺: 0.146 – 2.83 mg/L, NH₄⁺ modeling: 0.146 – 3.432 mg/L; actual TN: 0.442 - 5.55 mg/L, TN modeling: 0.442 - 5.852 mg/L, the average error of NO₃^-, NH₄⁺ and TN at the modeling graphs were 40.31%, 27.47% and 17.74%. The MSE and RMSE of of PO₄^3- in actual are 0.159 and 0.399 and in model are 0.000 and 0.016; TP in actual are 0.138 and 0.371 and in model are 0.000 and 0.003; NO₃^- in actual are 0.043 and 0.206 and in model are 0.000 and 0.000; NH₄⁺ in actual are 1.343 and 1.159 and in model are 0.005 and 0.072; TN in actual are 0.195 and 0.441, in model are 0.001 and 0.031, respectively. The result of modeled data was still in the range of environmental indicators was mentioned in much other research. It helps to control the development of environmental factors in the pond to optimize the fish production as well as reduce the impact to the received areas. The model need to be continuing research to identify the impact of external factors (weather, light, etc.,) and also reduce the errors for better management.