With hopes of increasing the supply of farmed fish and providing more food for the burgeoning populations, researchers at the University of Gothenburg, Sweden, are studying what happens in a fish's body when it eats.

Studies to find more energy efficient aquaculture for better fish fodder by researcher Henrik Seth from the University of Gothenburg's Department of Zoology have helped to increase understanding of the procedure of eating in general.

He explains that it has long been known that a number of changes take place in the body following food intake, including an increase in blood flow to the stomach and intestines. This happens in humans and other mammals as well as in fish. However, relatively little is known about the signals that trigger these changes and how they are regulated. Both the volume and the chemical composition of food play a role in how the body reacts.

"It's not just blood flow that is affected by its chemical composition, but also energy consumption in the stomach and intestines, and these factors are believed to be interlinked," says Seth.

If energy consumption in the stomach and intestines rises, an increased blood flow will be needed to supply the active tissue with oxygen and nutrients.

"Increased blood flow is also important for carrying away absorbed nutrients so that they can be used to nourish different parts of the body and to build up and repair different tissues."

The results of Henrik Seth's research also show that parts of a fish's nervous system are involved in this regulation, and that a number of hormones (including cholecystokinin) can affect this regulation depending on the composition of the food. It is primarily here that an increased understanding of this field could make it possible to produce fish feeds in the future that require less energy to be broken down and absorbed.

"It might then be possible to enhance the growth of farmed fish, which would greatly increase the efficiency of fish farming with less waste of energy," says Seth.