A method of operating a variable speed pump in an aquaculture system including a culture tank that houses aquatic life. The method includes monitoring a dissolved oxygen level in the culture tank, determining a dissolved oxygen threshold based on current respiration requirements of the aquatic life in the culture tank, and comparing the dissolved oxygen level to the dissolved oxygen threshold. When the dissolved oxygen level is below the dissolved oxygen threshold, the method further includes increasing a speed of the variable speed pump until a flow rate through the culture tank that maintains the dissolved oxygen level at or above the dissolved oxygen threshold is reached. The method also includes updating the dissolved oxygen threshold based on new respiration requirements of the aquatic life as the aquatic life matures through its growth cycle.
