An open sea fish cage includes a fish enclosure, a floatation collar, and a weight ring. The fish enclosure allows water to flow therethrough. The floatation collar engages an inboard portion of the floatation collar, and includes a plurality of floatation segments that are connected by flexible joints to adjacent floatation segments. A weight ring assembly is suspended from an outboard portion of the floatation collar with first tension members. At least most of the fish enclosure is disposed vertically between the floatation collar and the weight ring assembly.
