Lots of folks love them... I don't much care for them, but my experience is limited. I had a crayfish that was eating my fish and someone suggested Danios as a "safe" fish to have with the cray. So, I got some pearl danios. Beautiful, lively, interesting and very, very active. For other reasons, I eventually moved the crayfish to his own tank but left the danios with the rest of the community. Over time, I noticed they were nipping at fins and their constant activity was, I believe, making the other fish more aggressive. My Rainbow Cichlid, normally very docile and peaceful, was actively chasing just about anything that got near him yet he'd never done that before. Since removing the danios (and putting them in the crayfish's new tank), all the other fish have calmed back down to their normal peaceful selves. Just my limited experience.