You can put up to 40 ghost shrimp in a 10-gallon tank. As a general rule, you can keep three to four adult ghost shrimp per gallon of water. A 10-gallon tank can even house more ghost shrimp if a portion of them are babies or juveniles.
However, the rule only applies when you’re keeping a species tank. If you’re keeping your ghost shrimp in a community tank, then you should consider the other tank inhabitants as well.
For example, if you’re keeping them with fish, then you should know that most fish need a gallon of water for every inch of their body. Keep that in mind to avoid overcrowding your tank.