Working with fish, Nagaoka, Takaji, and Hohani (1955), use Rjutov’s equation (Eq. (6)) together with Plank’s equation (Eq. (1)) for the calculation of the pre-cooling+freezing times. They use the original Plank equation with the values of P and R for cylinders, plus the definition of an equivalent diameter De, to account for the non-cylindrical transversal shape of the fish. This expression is then multiplied by a factor similar to the one found by Rjutov for meat, with a factor 0.008 instead of 0.0053.