Those aren't stiphodons, but actually sicyopterus gobies, which get substantially larger, and appear overall, much meatier. This is a very new group to the hobby, so general care info is still a bit sketchy, and can vary from species to species. Have fun trying to identify exactly what you have though... What they do generally share, is a fast moving, rocky, riverine environment characterized by highly oxygenated water. They generally feed by rasping algae off of rocks, though some species are more willing to take meaty food than others. Males of many species display vibrant colors when courting females. Here's a link with some more info, and amazing photos of what some members of this genus can look like.