I'm not so sure about keeping them in regular freshwater for long term health, it seems the commonly available Bumble Bee Goby benefits from having at least a small amount of marine salt in the tank. They also enjoy being in groups and having some cover / caves available. I keep a small group in a light brackish tank (usually around 1.005 or slightly less) that I have planted with java fern, a crinum calamistratum, jungle val, and a couple other species I'm trying to grow in light brackish. They are very tiny, I think about 1.5" is about there normal size. Picky eaters though, they prefer live or frozen food.
Great little fish, full of character. Originally had 7 , but due to an algaecide now 3 in a 55 gallon planted (slightly brackish). They battle for there own little areas of ground, mostly with themselves... I keep a roundtail betta in the tank and he tends to mess with their little caves of choice, but they stand thier ground and sometimes even scare him off. A very jerky swimmer, quick sudden movements seem to be its forte..
Even though they are small in size, they will eat anything that moves that will fit in thier mouth that decides to stroll too close..(they dont do pellets or flakes) this includes baby cherry shrimp And Fry.. and will try to make it fit if doesnt..
I keep them in a freshwater ten gallon; three of them. I ocassionally throw in some marine salt just so they feel comfortable, Since they some from areas where the salt amount is always changing i try to mimick that.
I've been lucky enough to get five of these little guys through a LFS. They were sold to me as a full fresh water fish. I've kept them in full fresh water for about 5 months now and they are as grumpy as ever. They are very interesting and funny to watch when they invade each other's territory. They refuse to take and sort of pellet or flake foods. But After a week of starving my gobies have learned to accept chopped up frozen shrimp. They also get blackworms a few times a week. Awesome fish!!
Bumblebee gobies come in two distinct species. Brachygobius [I]xanthozona[/I] has perfect unbroken black stripes and is best suited for brackish, but will tolerate fresh water and B. [I]nunus[/I] has less well defined banded stripes, and occasionally black spots or broken stripes. It is not very tolerant of a fresh water environment. Technically the common name for B. [I]nunus[/I] is the Golden Banded Goby, although I have not once seen these two species clearly distinguished when on sale in fish stores. They are both ambush predators, preferring the "wait until it floats right past" method of hunting, they can be difficult to feed with frozen foods, and practically impossible to feed with dried or flake foods. Try to have a current circulating over the bottom of the tank when you feed them, so that the food will keep moving, whether it's thawed or living.
Gobies tend to breed in typhoon season, so if you want to trigger spawning then you should lower the level of water in the tank and add at least fifty percent fresh, chemically unconditioned cool water (around eighteen to twenty degrees Celsius) to their environment.
I totally love these little guys. I have one in a 50 gal planted. He's the last of 5. Very finicky eaters mine does accept tetra granuals. He loves to hide in my lace rock caves. Wish I could find more.