Abstract: The present invention relates to submersible fish rearing tank (100). The tank includes an exterior enclosure (17) forming a closed fish habitat. A utility transition element (110) provides a transition for at least one of a water inlet, a water outlet, a gas outlet, an air inlet, and connections for instrumentation, fixed to the exterior enclosure (17). At least one pump unit (101) is provided to pump water into the submersible fish rearing tank (100) to provide a pressure inside the submersible fish rearing tank (100) exceeding a pressure acting on the outside of the submersible fish rearing tank (100).