You’ve probably asked yourself this question on numerous occasions. Have I had enough or am I still hungry? Fish also eat a lot when they have the chance. But often they are fed far too little. How active their food intake is depends on their metabolism. Unlike a human, fish are ectotherm. The ambient temperature determines the intensity of their metabolism. In summer their metabolism is significantly faster than in winter. That’s why the feeding needs to be adapted to the time of the year. A balanced diet not only ensures a species-appropriate growth and the continuation of all the fish’s life functions, but also a strong resistance to disease.
- The frequency of feeding depends on the time of the year. At temperatures between 5-10 °C you only should feed 1-2 times per week, between 10-15 °C 3-6 times per week and over 15 °C 1-4 times per day. Juvenile fish even get fed 4-6 times per day.
- The amount of food always corresponds to the daily ration, which is to be apportioned to the individual feedings. In winter this amount corresponds to the weekly ration. Consequently you don’t feed 4 times the daily amount but each time only ¼ of the food. The food needs to be adapted to the jaw form and be easily taken up by the animals. Small and young fish therefore need smaller food than big fish.
- The type and composition of the food depends on the animals. Sturgeons, for instance, feed on microorganisms living on the ground, whereas koi feed mostly on plants and goldfish eat everything they can get. Nevertheless they get plant food. It is therefore very important to take into account the protein/fat ratio.
- As soon as the fish become active you can feed them. Myths which say that fish don’t need to be fed in winter/autumn are wrong. Most fish already show activity at 5-15 °C and want to feed.
- Use special winter food for the winter which is easy to digest despite their slow metabolism.
Despite all the calculations, the rule of thumb „ Only feed as much, as can be eaten within 5 minutes” remains best. This way you can see if the amount currently calculated is too much and polluting the water unnecessarily. As a basis you should use the following calculation:
A medium sized koi with 40 cm weighs approx. 100 g in our example. It thus needs about 20 g of daily food (temperature between 15-30 °C). With a stock of 20 koi this results in a daily ration of 400 g of food which is given in 3 feeds of 133,33 g each (morning, afternoon and evening).
With this amount the basic needs of the animals are covered and a healthy growth is ensured without the fish becoming fat. Additionally we recommend a protein/fat ratio of 4:1, e.g. with the JBL Koi midi .
This is how to determine the weight, even without a suitable container for your scales: How can I calculate the weight of my fish?