Miami Aqua-culture, Inc.

The most important thing a fish or shrimp farmer needs to know is how much oxygen is dissolved into his culture water.  We usually measure oxygen on a scale of parts per million (PPM), with 6-8 PPM being normal.    Temperature, salinity and altitude all affect how well oxygen dissolves into water, and how accurately a meter can measure the available oxygen.  No oxygen is obviously bad.  But low oxygen forces aquatic animals to make compromises in terms of blood circulation, growth and disease resistance that farmed land animals normally do not have to worry about.  Freshwater prawns, for example, start having oxygen stress at 5 PPM.  Improper oxygen management cost farmers money in the long run.