NEO Index literally means: natural, energy-optimised nutrition. This is based on the ratio of proteins to fats in the food. Looking at the season alone, the fish would only need half as much protein in winter (2:1) as in summer (4:1). But because not only the season (meaning the water temperature), but also the size and age of the fish, and food function (e.g. growth food = ProPond Growth) play determining roles, the der NEO index has been developed to deal with all these factors in one.
The fish’s living conditions are also considered with the NEO index and factored in the special FunctionFood varieties.
Your young koi will also grow without growth food (JBL ProPond Growth), but they will grow more slowly and their body will not develop the beautiful shape it does when using this food. JBL ProPond Color will bring out the colours of your fish more distinctively and also make sure that the fish will retain their beautiful colours after purchase - because retailers generally feed this food to show off their fish in their most beautiful colours. It will also help younger fish (mostly two years old) to develop their colours properly when they are 3-5 years old. If you regularly feed your fish with ProPond Color their colours will show up more intensely, even at an older age.