Damselfish with flourescent blue margins

GW Damselfish2.jpg

I need help with this damselfish. This fish is located on an artificial reef in about 50 feet of water in the northern Gulf of Mexico (Mexico Beach, Florida) I can't find a damselfish in my fish books that has these flourescent blue margins. One of my fish expert buddies thought it could be a different color variation of the Dusky Damselfish; however, I have never seen orange and blue juveniles in years of diving this area. The juveniles around here are usually some variation of blue and yellow, for instance, the one I have pictured is very common here and is probably a Cocoa Damselfish (note black spot on base of tail). Thanks for your help.

I find a few Damselfish very challenging

This being one of them. I don't think it is a Dusky, however it could be a Beaugregory or a Cocoa (the juvi in pic 2 can be a beaugregory too) I find these 2 particularly hard to tell apart. perhaps someone with more expertise can chime in. I believe both species can have the blue edge fins. I don't know if they are more likely to appear in one than another.

Now, if (i don't know) besides the similarities these species can produce hybrids then it really complicates things.

looks like a juvie Cocoa

looks like a juvie Cocoa damsel to me, due to the spot on upper base of tail. Beaugregory juvie has no spot on upper base of tail.

hadn't noticed the spot

You are right, I didn't notice the small spot on the upper tail base of the juvie. Juvie Cocoa would then be correct.


I ID'd the juvenile as a Cocoa Damselfish when I posted the photo, but funny thing is that with all my photos of this area I don't have any photos of adult Cocoa Damselfish. I have lots of photos of this juvenile with the spot on its tail. Between that fact and the blue margins on the adult damselfish, I am wondering if maybe we have a different damselfish in this area that hasn't been identified. I'll try to get a lot more photos this summer so I can try to back up my theory. ~Carol


Thanks. I know it's difficult based on 1 photo. My husband and I dive the area a lot in the summer so I will keep my camera ready to get more shots of this damselfish and any juveniles that may be around. Although we don't normally collect fish, we could possibly collect one if anyone wanted to get a closer look for study.


Does anyone else have the latest copy of Reef Fish ID by Humann and Deloach? The distinguishing features for the Dusky, Longfin, Beaugregory and Cocao Damselfish have changed. Apparently the length of the dorsal fins can no longer be used exclusively to distinguish between Dusky and Longfin and the spot on the base of the tail can no longer be used for the Cocoa and Beaugregory. :(

Here's a link to their website with the new damselfish pages: www.fishid.com/damselfish

Based on these new descriptions, I'm wondering if the first fish isn't a Longfin because of the thin bright blue edge on the anal fin. Perhaps the second is a Cocao based on the diagonal lines formed by the scale edges and the snout shape.

I'm not sure tho. These new descriptions have me a bit muddled.


Thanks for the link to the new book----yes, I'm using the previous edition. I've added some more photos from the same dive. We can rule out Dusky--I've never seen blue and orange juveniles in this area. All the juveniles have the black spot on the base of the tail. I will try to get more photos this summer now that I know I have a bit of a mystery on my hands. Maybe we have our own hybrid up here. This area seems to be a bit overlooked I think when it comes to the fish ID books; at least it was in the last edition. We have a lot of marine life here that are not ID'd as being this far north. ~Carol

Unindentified Damselfish

I found a photo among my husband's library of another one of these damselfish with the flourescent blue margins. You can tell this isn't the very same fish by the injury to its dorsel fin. ~Carol

Unidentified Damselfish

After looking at the links to the updates on damselfish indentification, I'm inclined to think this is either another color phase of Beaugregory, or a previously unindentified damselfish. Either way it's surprising there is no positivie ID on them, because they are fairly common in ths area. ~Carol

Based on all the links, I'd

Based on all the links, I'd lean towards saying they're all Cocoas... but I wouldn't be confident enough in that ID to put it on a survey.

Is there an expert we can ask? I'd like to know not only what an expert would ID them as, but also how the other damsels were ruled out.

Damselfish with flourescent blue tail

I have been doing reef surveys off the panhandle of Florida in anticipation of the approaching oil spill. These damselfish are on almost every dive from Mexico Beach to Panama City. I've posted more photos at http://www.pbase.com/carol202/damselfish.

Case Closed--Damselfish with flourescent blue tail

After posting the damselfish photos to my web site and putting some feelers out, two expert icthyologists independently identified the damselfishes as Cocoa damselfish with better development of the blue margins on the fins. Paul Humann, are you out there? Maybe you could include this color variation in your next edition since it's so common in this part of the Gulf (at least before the oil spill)..


Thanks for the update, Carol. It's good to have some resolution on this.

I still don't feel confident enough to ID one on a survey, but not being able to ID one from a photo was frustrating. Those damselfish are so common and I feel like a bad surveyor not being able to tell them apart.

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