All I know is that some are brackish water and some are freshwater, you can tell which is which by the stripes on their body, the fw stripes go all the way around and the bw stripes break off. Try the Oddball's forum for more help.
i have two that i keep with my dwarf puffers. they hold their own, but aren't aggressive. they love live foods, but will eat frozen. mine spend most of their time sitting on the bottom or in the caves and just grumping at me with those puggy little faces. one of mine has a spot on his middle yellow band, he's scarface, the other is capone. i'm still trying to figure out if if they are males or females (here's a great spawning article: http/www.aquaria.info/modules.php?op=mod...order=0&thold=0 )
i've never tried them in any other set up as they seem to like having all the territory they have in the puffer tank. they are both about 1 1/2 inches long, maybe a little less. neat little fish. have inspired me to try a bw tank in the future with bw goby varieties.