I think it is fair to say that most marine fish which inhabit coral reefs are generally colorful to some form or another. Be it solid colors, stripes, or spots -- all 7 colors of the rainbow are boldly represented on the fish and reefs of Cozumel. However, as a family, Pomacanthidae -- the Angelfish -- is perhaps the most ridiculously gaudy colored marine fish of all. This family consists of nearly 90 species across 8 genera, plus some localized hybridization in some areas of the world, and nearly all of them are intensely, if not majestically colored. Unfortunately for us, Cozumel sees only six of these beauties. For our blog post today, however, I will focus on just two species -- the Gray (Pomacanthus arcuatus) and French (Pomacanthus paru).
As you may have noted already, both these Angelfish come from the genus Pomacanthus. This is quite a diversely located genus as the 13 fish species are spread across all tropical seas. However, the Gray and the French Angelfish are the only two species of this genus which can be found in the Caribbean.
All Pomacanthus species have protrusible jaws and comb-like teeth, meaning these fish have the ability to extend and withdraw their jaw, the action causing a suction or vacuum to assist in feeding. It allows for a highly variable diet which may include sponges, tunicates, zoanthids, and various other soft corals, plus of course many species of algae. For our two feature fish, however, stomach contents of adults have proven to yield over 70% sponge matter with sponges ranging from nine different species. In contrast, the juveniles have been found to have stomachs entirely fully of only filamentous algae, or in some cases zonathid polyps. Thus it is fair to say the diet of the Gray and French Angelfish will change with age. In fact the juvenile of both species is known to setup a cleaning station in conjunction with other known “cleaners” -- an oddity among angelfish.
Both the Gray and French are most commonly observed as adult pairs, where they can be seen freely roaming a reef with little worry of its surroundings. However, in some locations with high population densities -- like Cozumel -- the Gray Angelfish has been know to maintain harems and even attempt to thwart the mating of consexuals. Angelfish are pelagic spawners, meaning they release their eggs and sperm into the water column where it drifts away becoming part of the planktonic food chain.
Around divers the adults are not shy. Divers can freely swim up to either French or Gray Angelfish, and in many cases the fish will swim right past our mask merely inches from our face. It seems as if you could easily reach out and grab one. While the fish are feeding they seem to be oblivious to our presence. When they are not face-down feeding they will cruise just a few feet above the reef in search of their next meal.
I remember years ago working in Honduras there was a large sand flat we would frequent. The angelfish would swim alongside the divers encouraging them to dig in the sand by fanning the sand with their pectoral fins. As divers we could dig quickly in the stand to stir it up (note: I highly suggest you do not do this -- you will regret it hahaha) and polychaete worms would get exposed and the angelfish would snap it up instantly. If we wanted to voluntarily get stung by the worm (see note above) you could grab it our self and holding it in our fingers the angelfish would take it right out of our fingertips. Conversely, the juveniles are quite shy and seem to be particularly afraid of divers and specifically my camera, often retreating into the reef structure until the evil camera has left.
Speaking of juveniles… many of the marine angelfish change colors as they age from juveniles to adults, and both the Gray and French Angelfish are among those which change. In fact you may have just wondered about the video above not matching the adults picture above it. Quite the color difference, yes? Naturally this color change does not happen over night. Below is a picture of both a French and Gray together as mid-adult -- note the transitional colors of the stripes slowly fading away.
Below I’ve pictured the French Angelfish on the left (first), and the Gray Angelfish on the right (second).These fish are nearly indistinguishable as juveniles.
The key to differentiating between the two species is in the tail. Have another look --
If you mouse-over the image it’ll reveal the species. The tail of the French Angelfish is a complete yellow circle, while the tail for the Gray Angelfish is an incomplete yellow border -- oftentimes with a clear (as seen) or white border.
Naturally if you have any questions about this give us a shout!
Until next time, stay Salty my friends…