Humans aren't the only ones to have to deal with this problem. The biggest threat to fish is being fed with only one kind of food, and with no variety as a result. If the food has been open too long, the vitamin content decreases. Please check whether the fish have a varied diet with different foods, ideally with different ingredients, and make sure that food containers are used up within a maximum of 3 months after they are opened. There are barely any vitamins left in the food 3 months after a food container has been opened. In that case, subsequent vitaminisation is then required.

There are no objections to supplementary feeding with vegetables like salad, cucumbers or peas, etc. for the species that this kind of diet is suited for. However, it is not advisable to feed these uncustomary foodstuffs too frequently, since deficiency symptoms will occur after a while. Salads and vegetables contain very low concentrations of protein, which the majority of fish needs. It has been proven that algae and aquatic plants have a different composition from garden vegetables, so the latter are unsuited as a long-term fish food.