A wellbore servicing fluid assessment method comprising introducing test organisms into a first section of a first tub, allowing organisms less than a first size to pass into a second section of the first tub, allowing organisms less than the first size to flow into a first section of a second tub, allowing organisms less than a second size to pass into a second section of the second tub, allowing organisms less than the second size to flow into a first section of a third tub, allowing organisms less than a third size to pass into a second section of the third tub, selecting test organisms of a desired testing size, dividing the selected test organisms into a control group and test group, subjecting the test group to the wellbore servicing fluid or a component, and assessing the acceptability of the wellbore servicing fluid or component.