Inter-comparison of some equations for evaluating fish daily ration by numerical experiment with an impulse-input feeding model

The rate of food ingestion by fish in an impulse-input type model is represented as a unit impulse or Dirac delta function. It is assumed that depending on the of food type, the stomach has a limited capacity. Maximal meal size is equal to the difference between the maximum stomach capacity and the food containing within, at any given feeding time. The content of the stomach of a single fish during 20 days is simulated by the impulse-input feeding model. Feeding frequency and meal size are randomly generated, while an exponential model describes gastric evacuation. Daily ration is determined from food quantities in the stomach at time intervals of 2, 3, 4 and 6 h, with five well-known food consumption equations. Lowest errors were shown by the Elliott and Persson equation and the second Eggers equation. The first Eggers equation showed the highest error. The first Eggers equation was associated with differences between the content of the stomach at the end and beginning of the sampling period (0–24 h).