Yes and no... Some females will be super aggressive. Fiona was a part of the battle-for-alpha they did, but she backed out once her tail was torn!! Savannah, Saharah, and two others were the meanest lol. Poor Rose died from damaged organs!

But I've had my original sorority in will platys, danios, tetras... No problem. But yes, diseases spread faster...
to avoid diseases: 1. quarantine all for 2 weeks before adding. 2. cycle the tank. 3. keep up with water changes. 4. stuff the tank full of plants to avoid stress.