What’s New in the Fish Division

This will be the first of an installment of posts on fish species cataloged in the Fish Division.  I really enjoy my work, particularly when I get to identify species that i’m unfamiliar with.  And when you consider that there are more than 33,000 species in the world (with more being described almost every day) i’m not ashamed to say that I anticipate being able to encounter unfamiliar species for a long time to come!

Recently one of our associates, Miriam Gibbs, found several boxes of specimens that probably were brought in during the tenure of former curator Milton Trautman.  Most of the vouchers were from a series of collections that were made by ichthyologists working off the western coast of Mexico below Baja California, particularly around the “Islas Marias“, or Tres Marias islands.  The Tres Marias are actually a group of four islands that until February 2019 was a Mexican white collar penal colony.  Most of the Tres Marias specimens were collected by divers using rotenone (The chemical rotenone interferes with a fishes’ mitochondrial electron transport, killing the fish.).  It is said that rotenone has ” has only minor and transient environmental side effects”.  I’ll stick with seining, electroshocking and trawling.  Here are a few of the species I’ve been adding to our collection (many of which are actually new to the OSU Fish Division), click on the genus and species name to go to a series of images hosted by fishbase.de:

scissortail damselfish Chromis atrilobata Family Pomacentridae (damselfishes)

Most damselfishes are marine, but a few are euryhaline and thrive in estuaries with some of those (such as the freshwater demoiselle) swimming upstream in rivers.  There are 28 genera and approximately 335 species, found primarily in the Indo-Pacific and Eastern Central Pacific oceans in tropical and warmer temperate areas.  They are primarily herbivorous, with large males grazing and maintaining plots of algal turf on and near coral reefs, but many are also omnivores, feeding on small crustaceans.  Many damselfish species can be quite aggressive, particularly those belonging to the subfamily Pomacentrinae.  Thus it is important to keep this in mind when considering aquarium tank mates, especially if the damselfish is an older, larger specimen.  However two exceptions that are fairly docile are species of the genus Chromis (one of which I’ve cataloged and will post on later), and clown, or anenomae fishes.  The scissortail damselfish is found in the Eastern Pacific, from the northern Gulf of California to northern Peru, including the Galapagos and Cocos islands.  They school in open water above the coral reefs and rocky areas where they live, feeding on zooplankton and often intermingling with king angelfish, another species recently cataloged. They are not as strongly territorial as other damselfishes in the area are. They are almost invisible in the darkness of deep water but for its brilliant post-dorsal white spot which gives the illusion of glowing in the dark.

Scaridae (parrotfishes) Nicholsina denticulata loosetooth parrotfish

The generic name for this fish species was given for J.T. Nichols, 1920-1941, a curator at the American Museum of Natural History. Almost all of the species in this family have teeth fused into a hard beaklike structure enabling them to crush the coral and rocks from which they scrape algae.  One exception being the loosetooth parrotfish, whose teeth are unlike those of their confamilials.  This species is found in the Eastern Pacific from the Gulf of California to northern Peru and the Galapagos Islands. They are abundant in shallow coastal areas, especially in rocky coasts with macroalgae.  They can be solitary or swim in loose schools, and feed by scraping or breaking off chunks of the reef and digest the algae that grows within, or they feed directly on algae.  Parrotfishes are actually responsible for some of the sand that creates beaches and small islands, biting off pieces of rock and coral with their jaw teeth, chewing the pieces with their throat teeth and excreting the byproduct.  For a look at the species that is ostensibly the best at making sand, check out these really odd looking humpback parrotfish on this fantastic BBC video.  These fishes exhibit beautiful colors, and change their colors as they develop from young to adult.  Most species in the Scaridae also exhibit sequential hermaphroditism, changing sex as they mature, mainly from females to males.  These life histories, combined with the ability of many species to mimic colors of other species as juveniles, makes it sometimes difficult to determine species identifications.  Fortunately for me, most of the specimens in our collection have already lost their carotenoid colors, leaving only the color patterns provided by melanins, and by guanine crystals under some fishes’ skins.

tiger snake eel Myrichthys tigrinus Family Ophichthidae (snake eels)

Most people interested in fish are familiar with the sinister looking moray eels.  The closely related but much less frightening snake eels are a fascinating group.  One of the differences between morays and snake eels is their tails: Species in the family Muraenidae (morays) have broad, flattened tails, whereas snake eels have tapered, pointed tails.  Many have only vestigial fins, lending to their snake-like appearance and aiding in their burrowing lifestyle.  It is said that if swallowed whole they try to burrow out of the attacker’s body, and have been found buried in the larger fish’s flesh.  Snake eels are found on sandy bottoms of coral reef areas and muddy bottoms of grass flats to 200 feet depth.  The primarily nocturnal snake eels make burrows in the soft bottom tail first, and hunt for crustaceans, octopuses and small fishes in and on the sand. They have no commercial value although they are eaten by individual artisanal fishermen. Several snake eels are rather attractive as you can see on fishbase, many species in the family make good aquarium pets (but make certain to keep a tight cover on the aquarium as they are known to slither out in search of food), and are said to be bold and easily approached by divers (in which case maybe you won’t need the rotenone?