Josh is correct. However the mistake has already been made and letting the fish go is a worse option. Luckily here we are dealing with a greenside darter, and it is hard to imagine any areas where they are threatened or endangered.
That being said, now that you know our policy, please do not submit any additional in tank photos for identification. It is very important ecologically that you don't remove fish from the stream until you can properly identify them. This protects both you, the fish and indirectly our organization. Had that darter been a listed species(endangered, threatened, or protected in any way) you would have just put yourself in jeopardy with the law. Believe me when I tell you that this forum is monitored by wildlife officials. Some even happen to be members. Ecologically, that goes without saying, I am certain you don't want to remove an endangered species from the wild and keep it from spawning and keeping the species and that particular population viable. And lastly NANFA cannot condone or tolerate the practice of removing unidentified fish from the wild. That is very contrary to our mission.
So in the future, your solution is to take streamside photos then release the unknown fish right back to the stream it came from. You can take photos in hand, but that is not ideal, as many fish are difficult to ID without a good in the water photo. Now the photo you posted is ID quality. Keep that quality up by getting a small acrylic container. A critter keeper tank from a pet store will work. Then you can go to home depot and get a piece of clear acrylic have them cut it, or cut it yourself. The idea is to make it just small enough that it will fit inside of your photo tank. Pretty tight fit. You can then use it as a paddle to gently squeeze the fish up against the front of your photo tank and take an ID quality photo streamside.Release the fish, get a definitive ID, then once you know it is legal and ethical, return to the stream and bring home a specimen or two.
Good luck, and now we should look forward to your streamside ID photos.
Now if we were wrong and you took that photo while snorkeling, then keep up the good work, and we would love to see more underwater photos of that quality!
Nevermind my last sentence, I see dried water droplets on the glass.
Edited by Matt DeLaVega, 22 July 2016 - 03:36 PM.