Unknowns from Isla Mujeres, November 2011


100_071 - 3 feet of water, grass beds/sand.  I'm really interested in the larger silvery fish below, but if anyone has any guess about the school of smaller fish above it, please let me know.

PICT0006 and PICT0016 - Probably the same species, occurring together @ 40'.  The second one is missing part of the tail.

PICT0065 and PICT0067 - Same fish in both pictures.  50 feet, Isla Mujeres

PICT0088 - 40 feet, Isla Mujeres

Any help is appreciated.  Thanks.

Fish IDs

The small, schooling fish are Hardhead Silversides and the larger fish below belongs to the Mojarra family (Gerreidae). Looks like a Eucinostomus specie. Check out the Flagfin Mojarra in Humann's book to see something similar.

Fish No. 2 looks like a Carribean Stingray. I thought they were mainly around shallow mangroves, but maybe they venture out into the deep.

The last three pictures are all Dusky Damsels, Stegastes adustus.


Thanks for the info. 

Thanks for the info.  Hardhead silverside for sure!  Couldn't figure that one out in the field, and they were everywhere.

At first, we thought the mojarra-looking fish were flagfins, but we couldn't clearly see any white below the black tip on the dorsal.  Then, it looked more like a slender mojarra looking at the slender mojarra video on the Reef Fish software - the fish in the video had clear dark tips on the dorsal fin - but the shape wasn't quite right.  Now, after observing hundreds of these and taking many photos, we think these are silver jenny.  Some of the indviduals had dusky bands across their backs, which fits with either silver jenny or slender mojarra.  What do you think?

We thought the ray was Caribbean stingray, too.  After reading the habitat description, we weren't so sure.  It was on a large, flat sandy area, just in deeper water than I would expect based on the habitat description.

On the damselfish, what characters are you looking at to differentiate between dusky and longfin?  In the shallows, we saw both dusky and longfin juveniles, so both species are known to be in the area.  I had tentatively ID'd the damsels in these photos as longfin based on a bright blue edge on bottom of anal fin (most visible on last photo), and the depth (>30 feet, although I can't be sure of the exact depth).

Thanks, and have a happy fishy new year.

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