In shrimp language grade S is better than grade B or even Grade A - more distinct color pattern and will develop to a better size. Our shrimp are S grade. Do not keep fancy shrimp with cichlids of any kind, for those fish they just look like food no matter what the color. Don't worry about the short life span, shrimp breed fast. Some of the chain stores quality on this shrimp is so bad they can only refer to it as red and white shrimp.
