Johan’s main research interest is nutrition; currently mainly on fish. Within fish nutrition he is
triggered by the large between species differences (marine vs. fresh water; trophic level; warm vs.
cold water) and their nutritional implications. He is focused on understanding how nutritional and
environmental factors influence animals regarding aspects like, feed intake regulation, digestive
physiology, energy metabolism growth and adaptive capacity. This is predominantly studied in light of
aquaculture issues, both at a group level as well as individual fish level (e.g., causes of individual
variation in growth).
The past nutrition research in the group was concentrated on feed-fish relationship. Current and future
research efforts on fish nutrition are more focusing on feed-fish-system relations. In intensive
aquaculture systems fish are next to the feed also strongly influenced by water quality (environmental
conditions). Therefore we focus more on the cycle “feed(intake)fishwastefeed(intake)”. These
feed-fish-systems relations are assessed regarding: 1) feed intake regulation mechanism (including
feeding behavior); 2) digestive physiology in relation to quantity and quality of faecal waste
production; 3) gut health (e.g., barrier functioning; microbial composition; enteritis) 4) nutrient
requirements (as affected by environment); 5) feed evaluation (e.g., net energy system for fish).
Wageningen University, Aquaculture and Fisheries Group (AFI)
De Elst 1, 6708 WD Wageningen, The Netherlands