Spotted Burrfish or Porcupine fish?

[ColoDale]

Is this a Spotted Burrfish or a Porcupine fish?

The fish does not appear to be inflated or partially inflated to me.

The photo was taken in Cozumel, Oct/Nov 2011 on a night dive on Santa Rosa Shallows at approximately 50 ft and the fish is 12-16 inches in length.

I identify it as a Spotted Burrfish due to the fact that the triangular spines should always be erect and are in this photo i.e. erect triangular spines but the fish is not inflated.

There are many similarities between the two, so which is it?

 

[koozemani]

Looks Like a Baloonfish

Balloonfish pictures and species identification

We see them in the sea of Cortez all the time. That pic appears uninflated.

 

[koozemani]

Maybe not, I just noticed the spots on the fins. But check the site I linked, it's a great resource.

Spotted porcupine fish would be my guess, but they're listed as pacific dwelling.

 

[Jim Greenfield]

Looks like the Spot-fin Porcupinefish - Diodon hystrix - to me. Have a look at http://www.fishbase.org/summary/SpeciesSummary.php?genusname=Diodon&speciesname=hystrix and go to the "All Pictures" link and see what you think. They are common in the Caribbean

 

[ColoDale]

I had a look at the Porcupine fish and all photos from the link. I am leaning towards a porcupine fish but there are several differences which make me unsure.

First, I cannot tell if the short description from the link http://www.fishbase.org/summary/Spec...esname=hystrix applies to the one fish on the page or all porcupine fish of this type. Assuming all Porcupine fish then there should be no dark splotches yet mine has at least 4 (under eye, before side fin, after side fin, and near tail). However the same link under all photos shows one from Belize that has very similar dark splotches as in my photo.
The Spotted Burrfish, Chilomycterus atringa, shows distinct dark patches. Note that there are only two photographs. These splotches then are indeterminate.

Second, is that the Spotted Burrfish is said to have erect triangular spines when not inflated. I see those near the tail on top in my photograph although the spines on the top of the body, away from the tail, don't appear to be triangular but elongated which is more consistent with a Porcupine fish. If the short description of the Porcupine fish is to apply to all Porcupine fish, then it says that there are no dorsal spines. I take this to mean those found along the spine on the tail in my photograph and they are evident. So it leads me away from the Spot-fin Porcupine fish to Burrfish.

Third, all the photos in fishbase.org of the Porcupine fish (Diodon hystrix) on the all photos page, are shown inflated except three and only one from Belize has similar coloring, markings and shapes. I must assume that this one from Belize has been classified correctly. One similar photo out of 12 does not inspire me to make a decision.


Fourth, the Spotted Burrfish seems to have a slight protruding belly and the Porcupine fish does not. This is from drawings from Humann and Deloach. My photo does not show this protrusion so it leads me to think it's a Porcupine fish.

Note that the Fishbase.org page for the Spotted Burrfish does not have much detailed description.

So, I have, in my mind, two indeterminate votes, one Spotted Burrfish vote and one Porcupine fish.

I have two other photographs, one head on and one fish butt. I will look at these as well and try to post them here.

Since I am wavering on classification, any input is appreciated.

 

[koozemani]

I would say it's definitely a porcupine fish, but what specific species I couldn't say. The balloonfish/banded porcupine show the same bands that appear faintly on the top of the fish in the pic. However, the description specifically states that their fins are not spotted where the fish in your pic clearly has spots on it's fins.

 

[ColoDale]

Here are the head on and tail shots.

The fishbase.org description for the Spot-fin Porcupine fish says "...flanks and fins light brown with numerous dark spots;.."
The Humann and Deloach says both have spots on fins.

So I am not sure which description is referenced for no spots.

The more I look at it, the more I think it a Porcupine fish but I don't know why and can't back up either type, Burrfish or Porcupine.

The spots overall on my photo are fairly consistent in size whereas the reference material I have seen for Burrfish, they vary in size. This may only be a variance of one particluar fish but I would assume it would be in reference material as representative.

Bands ar clearly visible on the top of my photo of the fish but I don't have any references to these specifically for what it means.
It's just that every porcupine fish I have seen in the area seemed smoother i.e. less spines and with not much banding.

Lastly, the fishbase.org short description for the spot fin Porcupine fish says no dorsal or anal spines. If I interpret this correctly, my photo has both and therefore it should not be a spot fin porcupine fish. Both my photo and the description of the spot fin porcupine fish say spiny belly.

I am still leaning towards Porcupine fish.

 

[deborahdelamar]

Porcupinefish (family) Porcupinefish (species). Besides the fact that seeing a Spotted Burrfish (also in the Porcupinefish family) would be considered extremely unusual or impossible in Cozumel, this fish lacks the dark, large spots around its face or body that are characteristic of that species. This looks just like a young Porcupinefish in its light phase. In addition to the Porcupinefish, the other members of that family here are the Balloonfish (common) and the Web Burrfish (occasional).

Maybe it's the color phase that's throwing you off? These fish can lighten and darken and it's the dark (grey) phase that we see the most. The fish's color bands are less obvious when it's in the dark phase.

Naming conventions are also troublesome. The common species name "Porcupinefish" refers to the same species as the "Spot-Fin Porcupinefish" that Jim references (Diodon hystrix.)

 

[ColoDale]

I agree that a spotted Burrfish would be rare in Cozumel and that the Porcupinefish are more abundant and that they are in the same family (Diodontidae)

I also agree about the larger spots on the face area of the Spotted Burrfish that are not evident on my photos here. It took me awhile to get that from ID photos but I realized that tonight while posting and hoping that it wasn't just an individual difference. So Deborah, I appreciate that concurrance.

I have seen Porcupinefish that were much larger and that the Spotted Burrfish is generally smaller from what I gather. I have seen balloonfish and I think Web Burrfish but will have to go through my photos for the latter.

It's not really the color that bothers me. It's the descriptions of the spines that are only supposed to be evident (erect) on Porcupinefish when inflated. The short spines that appear to be erect near the tail in my side shot photo that seem to be erect but the fish is not inflated. Therefore by what I read, it should be a Burrfish. However my interpretation of these triangular spines may be off and the fish may have been 25% inflated by being surprised when a coming around a corner at night and seeing a diver. I am trying to knock down any objections I have for my own classification.

I think this is a Porcupinefish and not a Burrfish.

 

[deborahdelamar]

Oh, it's the spines! All porcupinefishes show very obvious spines all of the time. These are lying fairly flat on the skin; far from "erect." I don't know where all the "evident spines" language comes from. I do know that Balloonfish can extend their spines without inflating -- perhaps this species can't and that's the explanation. Have no idea...

See photos http://www.fishdb.co.uk/findpicture.php?latin_name=Diodon hystrix