Fish ID

[mginani]

Can anyone ID the type of fish in the picture? We did not buy him but he showed up one day and has been steadily growing. My tank currently has a lawnmower Blenny, a clownfish, Royal Gramma, A Wrasse, and a Firefish. The Blenny and Clownfish have been in the tank for years. The Gramma, Wrasse, and two Firefish were added after being quarantined recently and one of the Firefish died after a couple of weeks in the tank.

 

[DSC reef]

Resembles a gulf killifish

 

[Maritimer]

+1 for killifish, but can't nail it down to species level.

There are several different species along the coast of the U.S. - do you have liverock or something from a particular region? That would be a good place to start looking.

~Bruce

 

[mginani]

No recent liverock has been added. Only thing is the fish from liveaquaria that I mentioned and some coral from battlecorals. Here is another photo. You’ll notice a distinct black spot/stripe at the front of its dorsal fin.

 

[Pbh-reef]

The black spot makes me think it could be a rainwater killifish, which lives in fresh and brackish water:
http://txmarspecies.tamug.edu/fishdetails.cfm?scinameID=Lucania parv
https://en.wikipedia.org/wiki/Rainwater_killifish

Other possibility would be gulf or bayou killifish:
http://txmarspecies.tamug.edu/fishdetails.cfm?scinameID=Fundulus grandis
http://txmarspecies.tamug.edu/fishdetails.cfm?scinameID=Fundulus grandis

But I think your fish's dorsal fin is too far forward to be one of those two. I'm no expert on killifish, btw, so could easily be wrong.

 

[mginani]

Only other thing that I remembered is that I did add Chaeto and Copepods.

 

[mginani]

Sure looks like it might be the rainwater killifish. I see that they lay their eggs in vegetation. Maybe it came from my Chaeto that was added?

 

[Pbh-reef]

Doesn’t seem impossible if there was water with the chaeto - while the fish is plain it’s a cool story to have a mystery fish in the tank!