Recently, I bought a Yasha Goby and pistol shrimp pair and placed them inside a 7g tank alongside a tail-spotted goby. After the initial day, the Yasha and shrimp have found each other and are now settled inside a small crevice inside a rock, while the tail-spotted goby has been settling next to a pvc pipe. While they seem to be getting along for the most part (besides the occasional territorial behavior from the tail-spotted goby), the yasha seems to be stressed. During the day it would eat fine and generally stay near its borrow with the shrimp, while at night, it would dart around near the surface. While I have a lid on the tank there is an opening area where the water is cycled through a filter and pumped back overhead the tank and back into the water, I’m worried it might end up jumping outside the tank. However, my main concern is this weird behavior from a goby that I thought to be a bottom dweller. Could this be an oxygen problem? or could this be a behavior that calms down after a while.