In response to population growth and its effects, there is a global need to find sustainable ways to exploit nutrient sources. Aquaculture is the fastest growing food production sector to meet global nutritional requirements and food security. Phosphorous (P) is a globally limiting nutrient used in commercial fish feeds, however, digestion of P by fish is inefficient. One species that may be well suited to RAS aquaculture in Europe and of economic importance is the European catfish (Silurus glanis), however little is known about the mineral requirement and uptake of phosphorous in this species. This study aims to reduce phosphorus in S. glanis aquaculture feed by determining if catfish can uptake P that has accumulated in RAS, directly from the water. The study tested the effect of increasing P levels in both the feed and rearing water to determine whether water-borne P could partially replace dietary P, reducing the costly use of P in feed. In a 42 day trial, growth performance, vertebral mineralisation, opercular and whole-body P content and Ca/P ratios were positively affected by increasing concentration of waterborne P in S.glanis fed with low P diets. P in water could save approximately 1g/kg of P in feed in terms of length of S. glanis. P requirement for S. glanis optimal growth is lower than for the species optimal skeletal development. Dietary phosphorus can be reduced in RAS aquaculture of S. glanis by the uptake of P from the water, thus, P could be reduced from S.glanis aquaculture feed.
Managing Thesis and Internship Exchanges
