Abstract: A differential air pressure system has a pressure bag with windows and preferred folding configuration such that when the bag is folded no window is folded. The pressure bag is supported by a lift support that is proximal to a user control panel and adjacent to or nearly adjacent to the user who is coupled to the pressure bag. A treadmill base for use with differential air pressure equipment is provided. There are various improvements provided to adapt the operations of the DAP system via the use of separate pressure volume and non-pressure volume portions of the treadmill base. Various improvements to serviceability and repairs are provided by placement of components outside of the pressure volume portion or by providing one or more pressure volume access points.

Abstract: Fish are cultured in one or more flumelike watercourses or "raceways" bounded by raceway-defining means. The water flow rate is such that the fish swim substantially continuously to maintain position. The fish are configured too closely to assert territorial rights, as they do when held at lower concentration. Water enters via a well enclosure at the upstream end, as by airlift upwelling; flows through the watercourse, sweeping waste materials along; and departs via a weir-like enclosure at the downstream end, where dissolved or undissolved waste is removed. Water is preferably supplied from and returned to a surrounding natural or man-made body of water, which also preferably floats the physical raceway means, facilitating water depth adjustment. Distribution of fish to adjacent raceways without any netting or handling conducive to injury is accomplished via airlift means. Fish so cultured remain healthy and grow rapidly and uniformly.