Cabo Pulmo fish geekery

Our trip to Cabo Pulmo was the first time we’d dived in the tropical East Pacific. A lot of the fish we saw resembled those we’d seen in Hawaii, Bali, and Samoa, but were just a bit different. Due to the vast, mostly islandless expanse of the tropical Pacific east of the 130th meridian the west coast of the tropical Americas is biogeographically distinct from the Central and West Pacific, so fishwatching in Cabo Pulmo left us feeling like beginners. Fortunately, the Smithsonian Institute offers a free app describing over a thousand East Pacific fish species. It’s aptly named Fishes: East Pacific. I don’t know how we’d have begun to identify the fish we saw without this comprehensive guide.

Delightful little Pixy Hawkfish (also called Coral Hawkfish) were everywhere you looked. Every coral head seemed to house at least one, and often several of these fish. While the majority of reef fish found in the East Pacific do not occur in the Central and West Pacific, the Pixy Hawkfish is an exception—it’s found all the way west to the Red Sea. This fish is very similar to the Dwarf Hawkfish I photographed in Bali in 2018: https://onebreathkohala.wordpress.com/2018/11/25/back-to-bali/

Someone familiar with Hawaiian and West Pacific reef fish might identify this head shot as a Fivestripe Wrasse, but they’d be wrong.

Here’s the whole fish. It’s a Sunset Wrasse, found only in the East Pacific. Its head resembles the Fivestripe Wrasse, while the body looks more like a Saddle Wrasse. Here are photos of the Fivestripe and Saddle I took back in 2015: https://onebreathkohala.wordpress.com/2015/05/14/fivestripe-wrasse/. (Man, my photos were pretty sucky back then.) All three of these species are closely related. The Saddle Wrasse is endemic to Hawaii, while the Fivestripe ranges widely through the Indo-Pacific region.

While the East Pacific has several species of butterflyfish, members of this family are not as abundant at Cabo Pulmo as we’re used to seeing in Hawaii or the Indo-Pacific. This one, the Blacknosed Butteflyfish, also called Barberfish, was the most common. The scientific name for this species is Johnrandallia nigrirostris, honoring the late Jack Randall, a true giant in the field of reef fish studies. Johnrandallia is a monotypic genus—nigrorostris in the only species. It’s another species confined to the East Pacific.

The lower fish in this photo was a special find. It’s a Clarion Angelfish. The primary range of this species is restricted to the tiny, remote Revillagigedo Islands, about 300 miles southwest of Cabo San Lucas. Only a few stragglers ever make it to the Baja Peninsula or Mexican mainland. This one makes a pretty pair with the adult King Angelfish above it. The smaller fish cluttering the photo are Scissortail Chromis.