Goby?

[Joey17]

I went to my lfs and saw a goby but i didn't recognize it. It was brown and kind of slender. I didn't know it was a goby until i saw that speicially modified fin on it's underside. Anybody got any ideas?

 

[TCTFish]

"Brown and kind of slender" can describe several different fish. Is it long slender or compressed slender? There are several species of gobies. The so called FW varieties are actually brackish. Many of them are brown. Some are long slender and some are compressed slender. A photo would be really helpful.