knight gobies water preference?

[Phoenixphire55]

I've read that knight gobies prefer brackish water, but I've also read that they do best in freshwater. Does anyone have experience with them? I think they look so cool and would love to have one, but he would have to go in the same tank as the shell dwelling cichlids and I don't think they would be happy with brackish water. Let me know anything you know about knight gobies if you've had one. Thankxxx!