Bumble bee gobys (aka BBG) are quite common, just about any one who owns a low-end brackish tank has them. They are not as easy to keep as you may think however. I own millions of them, one of my favorite fish.
Bumble Bee Goby
Another BBG link
The BBG in my avatar is slightly larger than most, but most BBG's will grow to about 1.25 inches. No they arent too lively because they lack a swim bladder, but they have a special pelvic fin which allows them to "hop" around and their anal fin allows them to cling to glass and other things within the aquarium. They dont swim, but watching them hop around is a lot more entertaining. If amecorrect 180 liters is roughly 50 gallons, its plenty large enough for BBG's. Is it a brackish tank and what are the current fish in there?
To make a brackish tank you need marine salt, not aquarium salt. The same salt used for saltwater tanks. You cannot house BBG's in your tank unfortuantly. Unless the pH is high and the water is hard you MAY be able to keep them, but the are far best suited in a slightly brackish tank.
Nope. pH should be at least 8 in a FW tank for BBG's. Ideally they should have salt added to their aquarium, producing a specific gravity of up to 1.005. I think I will rephrase my self, BBG's will 9 out of 10 times NEED slightly brackish water.