There are advocates of the zero diet for fish during the winter phase, but the following questions arise: At what water temperature does winter begin and when is it over? Why shouldn’t a fish get any food if it is still active and consuming energy?
We koi owners can see for ourselves that our koi are sometimes still active at 5-7°C water temperature. Activity is defined by the animals having to expend and consume energy. Without an energy supply, the animals have to draw on their body's own energy reserves and unfortunately this often leads to the energy reserves being exhausted in spring, thus increasing the susceptibility to disease. The dreaded spring viraemia is a typical consequence. That’s why many experts recommend feeding the koi until their activities stop completely! But: It has to be a properly designed winter food, as other food can no longer be digested and fermentation processes can cause extreme complications in the intestines. When developing the JBL PROPOND range, the ingredients were precisely adapted to the winter situation (low protein content of 18 %, no spirulina, but salmon and fish oil with a high fat content of 11 %). The NEO INDEX (natural, energy-optimised) shows the correct protein/fat ratio and takes into account not only the water temperature but also the age, size and living conditions of the fish. In winter food, the optimal P:F ratio is 2:1, rising to 3:1 in autumn and spring and 4:1 in summer. Only a growth food for small koi (5-15 cm) has a protein/fat ratio of 6:1.
There is another very interesting aspect that is taken into account in the JBL PROPOND winter food: The digestion of food costs the fish energy. In tests the JBL research department has found that there is food which costs the fish more energy during digestion than it replaces! This is fatal, of course, because the owners are feeding their animals, yet they’re still starving to death. For this reason a compromise had to be found between easy digestibility and energy supply. The desired result can only be achieved by the right ratio of salmon, shrimps, cereals, green meal, guar gum meal and fish oil. The animals then come through the winter and enter the stressful spring season with reserves, enabling them to become active in the fluctuating water temperatures, while still drawing on their reserves.
Please make sure that your koi are only fed while they are still active. The activity comes to a standstill at about 5-7 °C. Then do NOT feed them any more, let the animals draw on their reserves. Use a winter food such as JBL PROPOND WINTER, which has a protein-fat ratio of 2:1 and can be digested quickly. Then your animals will get through the winter without any problems and disease-free into the spring!