In 2026, GEOMAR inaugurated a new fish culture facility for experimental work on aquatic vertebrates. The entire system is housed within a climate culture room that enables accurate control of temperature and lighting conditions to simulate seasonal variations in the environment. The holding system is comprised of two 1000 L tanks to keep large species (such as Atlantic cod, Gadus morhua) and 15 glass aquaria for smaller species (such as stickleback). These systems can be operated both as a flow-through setup, to prevent pseudo replication of experimental treatments, or as a recirculating aquaculture system, with biological, mechanical and UV filtration systems. Flow-through sea water is supplied by the GEOMAR seawater pipeline from the Kiel Fjord (Baltic sea water ~15 ppt), a North sea water storage facility (35 ppt), or an artificial seawater storage facility (any ppt). A central gas mixing facility supplies custom gas mixtures into the environmental chamber for long term exposure experiments. These are carried out in nine 210 L tanks that can be individually controlled to simulate ocean warming, low oxygen saturation (hypoxia), and ocean acidification; thus, covering the major climate changes stressors affecting fish in the wild. Therefore, this state-of-the-art facility enables cutting edge research on the effects of climate change on marine fishes through acclimation, respirometry, exercise (swim tunnel) and behavioral studies at GEOMAR.