Beyond the Clear Walls: Adhesive Enigma (The Story of Gyrinocheilus (Algae Eaters))

Beyond the Clear Walls: Adhesive Enigma (The Story of Gyrinocheilus (Algae Eaters))


Hello and welcome to Beyond the Clear Walls,
a new series aiming to talk about aquarium fishes from a different angle than what you
usually see published and/or on the web. That is, we focus on the fish in nature and what
makes the fish unique morphologically and taxonomically. Aquarium care coverage… a
bit less important here. Today we talk about the Gyrinocheilidae, a tiny family of fishes
that has a less-than tiny role in the aquarium hobby. The family Gyrinocheilidae (“algae
eaters”) is a monogeneric family of fishes in the order Cypriniformes (Carp, minnows
and loaches). It consists of the genus Gyrinocheilus that currently contains 3 species: G.aymonieri
(Chinese algae eater), G.pennocki (Spotted algae eater), and G. pustulosus(Borneo algae
eater). To most aquarists and 97% people concerned with the family, aymonieri might as well be
the only species. Gyrinocheilids are distributed across Southeast Asia. This is one of the
least speciose families in the Cypriniformes (carp-like fishes), tied with the Vaillantellidae
(a group of loaches). This is significant because Cypriniformes is an extremely rich
and diverse taxon; these fishes represent a very small, unique group. They are highly
adapted to fast-flowing rivers and exhibit several adaptations to remaining stationary,
breathing, and feeding in these environments. The 3 species of Gyrinocheilidae are distinguished
by bodily markings, fin ray counts, and tubercle placement. Gyrinocheilus pennocki has 10 and
½ dorsal fin rays and sports spots on all fins. When young, the body has rows of distinct,
separate spots. These fade somewhat as the fish ages and the general body color darkens.
Its tubercles are located on the side of the head. The other 2 species have their tubercles
on the snout. G. pennocki is native to the Mekong River. G.pustulosus is distinguished
from its congeners by lacking spots on the fins and having a uniform dark body coloration
as an adult. No pictures of juveniles exist online, but they apparently have 3 rows of
dark spots. It possesses 9 and ½ dorsal rays and has facial granules that are not tubercles.
It is also found in the Mekong River. G. aymonieri also has 9 and ½ dorsal fin rays, but only
has spots on the caudal and dorsal fins. It possesses 2 rows of alternating spots on the
body and a small spot directly posterior to the top of the operculum. Like its congeners,
G.aymonieri is found in the Mekong River, but also extends into the Chao Phraya and
Malay peninsula. A feral population was also established in Puerto Rico, but its current
status is unknown, especially after Hurricane Irma. Pustulosus and aymonieri are more closely
related to each other than they are to pennocki, which hints that pennocki is the most basal
of the genus. Quick tangent here: these fishes have literally the worst set of common names
I’ve ever encountered. “aLgAe EatEr”. Thousands of fish species eat algae. That’s
like calling a horse “grass eater”. Like the subject of the video, horses indeed mainly
feed on grass, but boiling an entire animal’s identity down to a diet it shares with thousands
of other creatures leads to waaay too much confusion. In the fish trade, when someone
says “algae eater”, they could be talking about at least 20 different kinds of fish!
“Sucking loach” isn’t that much better. These fish are great at sucking, but they
aren’t really loaches! To make matters even worse, there’s hundreds of actual loaches
that do suck. Literally. But they’re not the subject of this video. Even though the
name positively blows, I’ll refer to the entire family as algae eaters. * Mouthparts modified into a SUCCing apparatus
* Transverse groove present on tip of snout * Barbels absent
* Pharyngeal teeth absent * Small incurrent slit above operculum
* Complete swim bladder * Skeletal stuff that I don’t have the time
to explain The most distinctive synapomorphy, or physical
feature that defines a clade evolutionarily, of the Gyrinocheilidae is the highly modified
mouth that allows them to attach to submerged surfaces in rapidly-flowing water. The lips
are greatly enlarged and fused together, with the rostral cap (a flap of skin above the
mouth) fused with the upper lip. These lips are lined with inward-facing keratinous hooks
with cutting edges that provide friction and aid in scraping edible matter off of surfaces,
kinda like a tadpole.( Imagine not having your lips coated in fingernails. This post
made by the Gyrinocheilus gang). A bit of etymology for ya: Gyrinus means tadpole in
Greek. Cheilos means lip. These guys’ family name literally means “tadpole lips”. They
are also supported by highly flexible mucochondroid tissue (Ralphs and Benjamin 1994). Mucochondroid
tissue is gelatinous connective tissue found in the heads and under the skin of teleost
fishes. The mucochondroid tissue helps support the lips and protect them from pressure-induced
damage. The lips are also fringed with papillae (fleshy cellular growths) around the circumference.
The mouth opens in the center of the lips and has 2 blind cavities directly below it.
These are literally organic suction cups. When the sucker is not in use, it folds up
under the head in 2 post-labial (behind the lips) grooves, reducing drag. The lip margins
resemble crescents when the sucker is idle. Suction is produced by the fish widening its
lips, pressing its mouth against a surface, and closing the oral valve. Water is expelled
from the lips, creating a vacuum not unlike that of ,well, a suction cup. The blind cavities
below the mouth expand and create a greater area for suction. While the sucker is in use,
water is unable to enter the mouth (Benjamin 1986), making it a sucker closed from outside
interference. When the fish is feeding, it opens and closes its sucker rapidly against
a surface. This allows the fish to rasp off any encrusting material on the rocks it inhabits.
According to an experiment done in Canada in 2006, this type of suckermouth appears
to be much more efficient than the open suckers of loricariid catfishes (plecos). The fish
has a greater adhesive strength while using less energy than an open sucker, which operates
as the fish breathes. However, the closed sucker only allows the fish to orient themselves
in one direction at rest. Loricariid catfishes can reorient themselves at will, but keep
in mind their suction is tied to their breathing, which uses more energy. My personal anecdotal
evidence proves this true (at least the strength part), as algae eaters always seem to find
themselves stuck to the bag when I bring them home, unlike plecos. Maybe it’s because
they come from faster waters than plecos and friends. Most fishes use their mouths to breathe.
Because of their highly specialized oral morphology, gyrinocheilids have lost this ability, at
least when they’re stuck to something. Instead, the fish inhales through a small slit directly
above the operculum (gill cover) that’s guarded by a valve. This slit directly opens
into the pharynx (throat), and the water is ejected from the lower half of the operculum
when the fish exhales (Jayaram 1950). This method of breathing allows the fish to breathe
and maintain suction simultaneously. However, less water flows over the gills than a fish
that breathes with its mouth. This means that less dissolved oxygen is potentially absorbed
by the fish. To maximize the amount of water flowing over the gills, gyrinocheilids breathe
more rapidly than other fishes. Mature gyrinocheilids, like many other cypriniform
fishes, possess tubercles on their heads. These keratinous growths are present in both
sexes of the fish. To the uninitiated eye, it makes the fish look like it has the worst
case of acne. Both tubercles and acne appear when the animal in question is going through
hormonal changes, so it’s not the worst comparison. The location of the tubercles
is a major diagnostic character for distinguishing the 3 species. Their purpose is currently
unknown. Considering they’re rough and only present on mature specimens, I’ll leave
you to draw your own conclusions. Another feature found in mature gyrinocheilids is
a transverse groove on the tip of the snout. This groove, made of fibrous thickenings of
the dermis (the layer of skin directly below the visible epidermis), serves as an anchoring
point for the supportive mucochondroid tissue near the lips and allows for the joint between
the maxillae (upper jawbones) and neurocranium (skully bits holding the brain) to move (Benjamin
and Ralphs 1994). Since this joint is movable, the fish can use its oral sucker without it
getting damaged by excessive force. Noticeably, gyrinocheilids lack barbels, and
less noticeably, pharyngeal teeth, both of which are major diagnostic features of most
cypriniforms. Barbels (like the whiskers on a catfish or carp) serve as sensory organs
to help the fish find food. Pharyngeal teeth are located in a fish’s throat, on the last
couple of gill rakers. They’re pretty useful if you swallow things whole. Despite lacking
pharyngeal teeth, algae eaters do possess dermal plates on the gill rakers. Gyrinocheilids
probably lack these features because of their diet of encrusting matter on submerged surfaces.
They do not have to process their food beyond swallowing or look particularly hard for it.
Strangely enough, gyrinocheilids possess a well-developed, though small, swimbladder.
Swimbladders are organs that fill up with gas to help the fish remain buoyant. A swimbladder
would ordinarily only hinder a bottom-dwelling fish like Gyrinocheilus in remaining stationary
in moving water. Doesn’t stop them from sinking like rocks though!
Gyrinocheilids have had a long history of being taxonomically unclear. People have struggled
throughout the ages to figure out what these fishes are related to. Even to this day, aquarium
books and websites don’t know where to place these things. “They’re catfish! No, they’re
…. loaches? Idk who cares let’s place them in “Miscellaneous” Hold on tight;
this is gonna get confusing. The first species described, G. aymonieri (Tirant 1883), was
initially described as a Psilorhynchus, another genus of unclear affiliations in the late
19th century. (Psilorhynchus has its own family now, depending on who you talk to. Yay! They’re
basically flattened minnows that live in Himalayan streams. Congratulations. You now know more
than 99% people about these fishes) Back to our video’s main subject, the genus Gyrinocheilus
was erected in 1902 to describe G. pustulosus. G.aymonieri was not very scrupulously described,
and was placed in Psilorhynchus until 1935. Gyrinocheilidae was also initially considered
a subfamily of the “Homalopterids”, a name which now refers to the modern Balitoridae
(elongated hillstream loaches). Regan noticed the well-developed swimbladder and lack of
barbels and realized the fish is not a member of that family in 1911. However, he placed
Gyrinocheilus among the cyprinids.The Gyrinocheilidae was erected in 1923 by Hora. His reasoning
was that, (read in different voice, or let some other guy do it) “ there seems to be
little doubt that judging from their appearance the members of the genus Gyrinocheilus are
remarkably similar to those of the genera Crossocheilus and Garra, but this outward
similarity, in my opinion, is directly correlated with the life of these fishes in moderately
rapid running waters. The presence of the slender toothless lower pharyngeals , the
structure of the scales, the remarkable modification of the gill. openings to form inhalent and
exhalent apertures and the structure of the mouth, lips and jaws are in my opinion better
defined characters than those that seperate(sic) Cyprinidae, Cobitidae and Homalopteridae from
one another.” By now, I hope we’ve established that the
Gyrinocheilidae is a distinct clade. Where the Gyrinocheilidae are placed in relation
to all the other cypriniform fishes is another question. If I haven’t mentioned it yet,
Gyrinocheilids have an eclectic grab-bag of primitive and derived skeletal characteristics.
Many of these are shared with loaches and suckers, while others don’t appear outside
of this one family. Relatively few are shared with actual cyprinoids. To keep it short,
they probably are most closely related to the suckers, which ironically don’t share
a native range with them anymore. Or they could be their own clade, either basal to
the rest of the cypriniformes or sister (the nearest evolutionary relative) to the Cobitoidea.
Before a controversial paper (Stout, Tan, Lemmon, A. R., Lemmon, E. M., & Armbruster
2016) was published that proposed splitting the Cyprinidae into multiple families, the
Gyrinocheilids were considered part of the Cobitoidea (loaches), possibly sister to Catostomidae
(suckers), which in turn is sister to the rest of the Cobitoidea. So basically related
to the loaches’ closest ancestor, if that makes any sense. One of the common names from
earlier now makes a tiny bit more sense. Those other two groups are comprised of largely
benthic (bottom-living) riverine fishes, which Gyrinocheilus happens to be one of. Catostomids
are cypriniforms that also lack barbels and suck food off the bottom with large modified
lips, so they were and still are often viewed as closely related groups. Some catostomids
even somewhat resemble Gyrinocheilus in appearance. However, catostomids have pharyngeal teeth
and are unable to adhere to submerged surfaces with their mouths. A few recent papers appear
to place gyrinocheilids at the base of the cypriniform family tree, sister to all other
cypriniforms.(Stout, Tan, Lemmon, A. R., Lemmon, E. M., & Armbruster 2016) and in their very
own clade. Their conserved diploid karyotype genome of 2n=48 appears to strengthen this
hypothesis. According to a Japanese paper published by the Linnean Society, the lineage
leading to the Gyrinocheilidae split from the Cyprinidae/Catostomidae roughly 151 million
years ago. This data is based off of molecular evidence, as Cypriniform fossils in general
are fairly rare and nobody has found any older than the early eocene. The earliest cypriniforms
themselves only appeared 155 million years ago, around the time Pangaea broke up. However,
this molecular evidence was based off mitochondrial dating, which often leads to overestimation
of species divergence times. Yes, the direct ancestors of algae eaters you can buy at any
pet store might have shared space with non-avian dinosaurs. Think of all the cool stuff these
weird sucky fish outlived! *Dabs aggressively* Said paper also claimed the Cypriniformes
originated in Laurasia, or modern-day East and South Asia. Some of the basal representatives
of some of the main clades of the order (Cyprinids, loaches, algae eaters) are found only in Southern
Asia, which is a sign the lineage originated there. Since many of these clades tend to
be bottom feeding fishes, it’s implied that the cypriniform ancestor was indeed a bottom-feeding
fish like Gyrinocheilus. The Japanese article also implies many of the benthic basal cypriniforms
competed with each other heavily, leaving some families strangely small compared to
others. Remember when I said the suckers don’t share a range with Gyrinocheilids anymore?
They were mostly eaten out of house and home by actual cyprinids and fled to North America
for the most part. Also notice how tiny and hard to accurately place Gyrinocheilidae itself
is. The other Gyrinocheilids (if they ever existed) must have had to take on this highly
specialized form to avoid the intense competition of the possible cypriniform explosion of the
Mesozoic. A newer paper seems to again place the group in a clade with the suckers, but
this paper appeared to focus more on knifefishes and characins. This paper also dates the differentiation
of Cypriniformes around 98.6 to 84.7 mya, with Gyrinocheilidae + Catostomidae appearing
73.6-60.5 mya. Still a fairly old lineage, but not putting some dinosaurs to shame. Yet
another, more recent (2017), journal article places the family as sister to the Cobitoidea.
Again. It also called out the Japanese paper for overestimating the age of the Cypriniformes.
For those who still want to dab on the dinosaurs with your weird Laotian sucky thing, the paper
still claimed the group arose before the K-T extinction event. No matter how you slice
it, the Gyrinocheilidae is a fairly basal, yet very distinct group within the Cypriniformes. Gyrinocheilids are egg-scattering fishes that
spawn in the spring and summer (Apitanakul and Wetkachul 2002). Their eggs are semi-buoyant,
so they can reach the bottom of a different stretch of river than the parents spawned
in. Yep, algae eaters are amazing parents. Just drop their gametes and run. The larvae
feed on phytoplankton starting at 4.5mm long (Termvidchakorn and Hortle 2013). Strangely
enough, the larvae possess a superior (upturned) mouth with separate lips until about 14mm
long, when their trademark lips develop. The fish begin to scrape algae off of surfaces
when they become postlarvae. Juveniles travel together in large groups. In the wild, G.aymonieri
inhabits river basins with hard surfaces they can graze on. Typically they spend their days
in rock crevices. They migrate to floodplains when the water level rises. Pennocki is known
to migrate from December-February, or around Chinese New Year time. G.aymonieri usually
feeds on algae and detritus, but is known to occasionally consume small crustaceans
and insect larvae. They prefer thinner layers of encrusting matter, and defend their patch
of algae and slime from any intruders. Stomach contents in one study found mostly algae in
an unspecified number of specimens. All 3 species grow to a maximum size of slightly
less than 30 cm (12 in) SL. Gyrinocheilids are a food fish in their native
range. Tasty. Small ones are used in soup and fish sauce, while larger specimens are
sold in local markets like most other foot-long fishes (Termvidchakorn and Hortle 2013). Judging
by their diet and relations, assume they taste like grass and mud with a side of bones. G.
pennocki and G. aymonieri catches are very important to the local economies of their
native range. Since they are impossible to catch with a hook and line, gillnets and traps
are placed in rocky rapids stretches instead. Luckily for them, they aren’t fished with
bombs and automatic rifles like other fishes were in their native range at one point. In
fact, their populations are declining somewhat because of overexploitation and damming. The
effect of damming on population health of these two species has yet to be fully explored
(Allen 2011), but since these are migratory riverine fishes, it’s best to assume the
worst. It is known that siltation in the rapids where pennocki lives kills the algae they
feed on, leading to smaller catches. Despite this, both species are listed as “Least
Concern, population decreasing” by the IUCN. I mean, if you can find them at PetSmart for
$2.19, they can’t be THAT rare. Little information is known about G. pustulosus’s conservation
status, as it has not been evaluated by the IUCN. Outside their native range, the “Chinese”
algae eater G. aymonieri, is an extremely common aquarium fish. It’s unknown how they
got this name, as they rarely occur in China and are much more common in Thailand. Aymonieri
is occasionally known as the Siamese algae eater, but that name already belongs to another
fish, the Crossocheilus mentioned ever-so-briefly earlier! Again, see why common names stink?
They are apparently bred in massive quantities for this trade (explaining their price). Therefore,
wild G.aymonieri are rarely encountered in aquarium shops.
The other two species are rarely encountered in aquaria, with G. pustulosus probably never
being intentionally imported. Pennocki comes in very sporadic shipments. Most aquarium
keepers buy G. aymonieri to rid their tank of an algae problem. However, “Chinese”
algae eaters are generally said by many hobbyists to be a poor choice to solve an aquarium’s
infestation of algae. (By the way, clearing algae isn’t a good reason to buy a fish
anyway. Aquarists, buy fish because they’re cool, not a job they can do for you.) As young
fish, they will eat algae and not bother other fishes in aquaria. As they age, they supposedly
learn to eat fish food and ignore algae (which is in direct opposition to their wild diet),
grow to unmanageable sizes, and can be territorial to other fishes in an aquarium, especially
other bottom feeders. The “Chinese” algae eater will even attach themselves to the sides
of slow-moving or flat-sided fishes and feed on their slime coat, causing injury to the
other fish (Frank and Sarakontu 2011). It is unknown why the fish does this, but gyrinocheilids
do also ingest the encrusting organisms living in algae and those aren’t common in most
fish tanks. Nutritional deficiencies perhaps? Bored? Who knows? Despite these drawbacks,
the fish is still somewhat popular amongst aquarists and widely sold in pet shops worldwide.
There are even albino, golden, piebald, and short-bodied forms available for sale, which
is probably a result of artificial breeding. Speaking of breeding, aymonieri has only been
bred once in captivity as far as we know, which was entirely accidental. It involved
a drastic change in water conditions, hinting at the fish’s migratory lifestyle.
A possible reason for their popularity is their low price compared to other fishes,
ubiquity (you can seriously find these guys at Walmarts that sell fish), tolerance of
a wide variety of aquarium conditions, and less “alien” appearance compared to plecostomus
(they look like fish and not dinosaurs). Despite me mentioning their ubiquity in many pet stores,
some online shops don’t sell these fish because of their bad reputation, According
to data taken in 1997, each individual “Chinese” algae eater is worth 6 U.S. cents, lower than
any other fish in the paper (Chapman 1997). They also resemble other cypriniform fishes
that do a better job of eating algae and are less likely to attack other fishes (like Crossocheilus),
which leads to confusion among less-experienced aquarists. (Cue montage of n00b fishkeepers)
In their defense there’s a ton of pencil-shaped grazing cypriniforms with a horizontal stripe.
More experienced aquarists tend to avoid CAE like the plague, because they don’t “do
their job” and attack other fishes instead. (Cue montage of CAE hate) “Chinese” algae
eaters tend to live near the bottom of aquaria, since they are negatively buoyant. Their sucker
mouths allow them to climb the walls of an aquarium and attach to any submerged surface.
They are also a crepuscular species preferring to be active at dusk, just like the plecos
that a few tasteless people find ugly. Since G.aymonieri is very easy to find in pet shops,
it is a common specimen to use for molecular phylogeny of other fishes, especially other
cypriniforms. The other two algae eaters probably behave very similarly, but since they’re
almost never intentionally imported, who the heck knows? Honestly, you can find more info than you
could ever want on how to care for G.aymonieri online or in various aquarium books. Remember,
aquarium care is NOT the focus of this series. Just make sure they get tons of space, clean
water with good flow, and adequate amounts of food. This probably applies to the other
two species, if by some miracle you come across a specimen. And that’s Beyond the Clear Walls with the
Gyrinocheilus fishes. Honestly, the Chinese algae eater is one of the most mistreated
fish within the aquarium hobby, about a tier below goldfish and bettas. I made this video
to give it and the other two members of the genus their proper due as interesting animals
in their own right, not as algae cleaners shoved in too-small tanks or heavily badmouthed
by well-meaning hobbyists. Honestly, who hasn’t kept aymonieri in an aquarium? Have y’all
seen the other two species in person? Eaten an algae eater? Let me know in the comments! .

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