I have a swarm in with Figure 8 puffers and American flagfish in a brackish tank. I believe there are freshwater and brackish bbg's and it's not good to put them in with fish like knight gobies that will see them as food. I'd be inclined to keep them in a species only tank but can't give any comment about keeping them with other fish. Try the brackish section as Neale Monks knows alot about these fish