The problem is that there are many species of "ghost shrimp". Some are more aggressive than others. The ones sold in most parts of the U.S. are not aggressive. I am talking about the ones with a red band around each little claw hand and the ones with faint white or darker spots or strips. Almost look like a tiger shrimp but clear. I have both of these types and they get huge. I have never seen them harm a fry or small snail. I have seen them take food away from a grown molly. Do some research about ghost shrimp in your area to see if you can identify the species. Ask your seller what the scientific name is and research that.