These reproduction rates are similar, one litter a month. The easiest shrimp to breed should be a big-eyed thief, because the black shell shrimp is small and easy to throw away its oocysts when it is frightened. Compared with black shell shrimp, guppies are easier to raise, because all shrimps have higher requirements on water quality. As long as there are shrimps living in the waters, the water is relatively clean, while guppies can tolerate slightly polluted water.