Plecostomus in Nature

Plecostomus or Hypostomus plecostomus belong to the family Loricariidae. Loricariidae means armored catfish. This taxonomical classification describes the armor-like longitudinal rows of scutes that cover the upper parts of their bodies. This armor is actually composed boney platelets as opposed to the scales normally associated with fish. Loricariids are the largest catfish family with 684 species in 92 different genera. The actual number of species belonging to this family can only be estimated. There are new species being discovered annually with still others awaiting scientific classification. The translation of the word plecostomus, like most species names, can be broken down into two parts. Pleco means pleat as in a fold in fabric. Stoma is mouth. Put the two together and you have, “folded mouth.”

The taxonomical designation plecostomus only describes a single species of armored catfish within the family Loricariidae. There are, however, over 50 classified species and at least 200 more that have not yet been scientifically described. Those awaiting official classification are given a numerical value preceded by the letter L. All these species have the shared trait of ingesting algae as part of their dietary intake and have become known worldwide as algae eaters. The name plecostomus, although not scientifically accurate, is used interchangeably when referring to these algae eating armored catfish. The two most frequently used derivatives of this synonymous “blanket” term are plecos or simply plecs. Plecs are native to Panama, Costa Rico and South America.

Plecos are inarguably one of the most popular and easily recognizable fish on the planet. Their unique, quintessentially pre-historic, appearance undoubtedly contributes to their global appeal. The fact that they look like a throwback from the era of dinosaurs is not coincidental. Their presence on Earth predates the emergence of mammals. Fossil records of Loricariids can be traced all the way back to the Miocene period. Owning one is like having a living fossil in your aquarium. It is, however, their dietary habits that have won them a home in so many aquariums around the world.

Tropical rain forests offer some of the most diverse and environmentally challenging scenarios nature can produce. Plecos populations flourish in every conceivable facet of these tropical regions from the brackish and often black acid coastal waters of inland estuaries to torrential mountain rivers and swift flowing streams. Their geographical distribution rises from sea level up to 3,000 feet in elevation in the steepest heights of the Andes Mountain Range. They can even be found in lightless subterranean habitats where few fish would dare to venture.  Nature has provided them with a number of highly developed coping mechanisms to help them survive the plethora of conditions with which they are faced.

One of the most easily recognizable of these mechanisms is their wide, suction-cup like mouths. This is a highly specialized feeding apparatus for what in essence is a bottom feeding scavenger fish. In addition to its most obvious application, this suction mechanism’s secondary function can best be demonstrated by watching a plecos cling seemingly effortlessly to the side of an aquarium.  This same ability helps to keep these fish anchored securely in place through the most torrential floodwater run offs the rainy season has to offer. A plecos will emerge from even the most severe rainy season in the feeding grounds it has become accustomed to where other less adaptable species have been swept countless miles downstream. Their distinctive and highly developed mouths have also won them the nickname, suckermouth catfish. 

The dry season brings yet another environmental challenge. Where water was once in abundance evaporation now threatens the complete annihilation of smaller aquatic ecosystems. This impending doom demonstrates the Darwinian Theory of survival of the fittest in its quintessential form. Armored catfish have highly developed digestive tracks. Their stomach lining and intestinal walls are saturated with literally millions of capillaries that have the innate ability to absorb atmospheric oxygen. They breathe air! Plecos species have been documented to survive outside of water for up to 30 hours. If this survival mechanism is not impressive enough in and of itself, armored catfish are also capable of walking on dry land. They use their pictorial fins and their caudal fin as a means of propulsion. They have been known to traverse considerable distances in search of a new home when rain waters start to recede.

Plecos are nocturnal creatures. Most nocturnal species have little choice but to seek shelter to avoid the glaring daylight sun. Armored catfish have developed an alternative solution. They have an iris operculum (Latin for little lid) incorporated into their eye. This protective mechanism is frequently called an omega iris because of the distinctive horseshoe shape it creates while protecting these fish from harsh sunlight. The iris descends from the top of the eye while the pupils simultaneously contract to restrict the amount of light that is allowed to enter the inner eye. This combination results in the exposed part of the pupil taking on the shape of an upside down Omega from the Greek alphabet. Perhaps the easiest way to picture it is to visualize the moon as it goes through its cycle to form a crescent.

Plecos are officially classified as omnivores. A more scientifically accurate description might be detritivore or detritus feeder. While it is true these extremely efficient scavengers will eat pretty much anything, the majority of their dietary intake is not derived from the consumption of algae. It is from ingesting detritus, or decomposing matter, foraged from the bottoms of streams and riverbeds. This is the true function of a scavenger fish, to survive off the garbage left behind by a flourishing ecosystem. They are, in essence, nature’s janitors. Hence the term bottom feeder.

Being a nocturnal bottom feeder can present its challenges. Here again nature demonstrates its infinite diversity in the armored catfish family. The first and most obvious is the presence of barbels. Barbels are slender, whisker-like organs near the mouth or nostrils. They are present on all catfish and virtually any other aquatic species that scavenges for its survival. These are highly developed tactile organs with taste buds incorporated into them. They make it possible for bottom feeders to search out and identify food sources in the murkiest water conditions. In addition to barbels, taste buds cover almost the entire surface of an armored catfish’s body including the spines on their fins. They are uniquely capable of searching for food in places completely devoid of light. This explains their presence in subterranean environments.

Since the complete globalization of the hobby fish industry took place shortly after World War II, several aquatic species have established populations in previously uninhabited ecosystems. Aquarium trade related releases are responsible for non-indigenous nuisance species costing million of dollars in ecological damage. In a day and age where both national and regional governments are forced to devise and implement AIS (Aquatic Invasive Species) removal and management systems, plecos varieties are among the few species that have been intentionally introduced into the wild. Plecostomus populations have proven extremely beneficial in freshwater systems prone to excessive algae growth. They have helped to neutralize this problem in Puerto Rico, Vietnam, Bangladesh, and Hawaii. It should be noted that ecologists have since cautioned on the unforeseeable consequences of introducing nonnative species into established ecosystems. Despite their obvious beneficial attributes, aquarium trade related releases have resulted in plecos being labeled as nuisance species in Florida, Texas, and the Philippines.

Plecos in Aquariums 

The name plecostomus applies to a single species of armored catfish. The actual species, plecostomus, can reach an excess of 2 feet in length. They routinely grow to a foot or more in the confines of an aquarium. The terms Plecostomus, Plecos, and Algae Eater, on the other hand, have become generic labels in the aquarium trade industry. They encompass a variety of Loricariids all of which are breeds of armored catfish. The adult size of these individual species varies considerably. If you have a smaller aquarium you can still enjoy the benefits of an algae eater. The variety commonly marketed as the clown plecostomus only grow to 3-4 inches. The king tiger plecostomus will top out at about 6 inches. This information is usually included as part of the “product description” both on the internet and in local retail stores. If the information is not present, ask. Choosing the right size maintenance fish for the right size aquarium will save you from future headaches down the road.

Loricariids are bottom dwelling creatures. They are a solitary species. They will tend to ignore the activities of their fellow tank mates. This makes them excellent candidates for community tanks. Naturally, they will stray from the bottom their substrate domain to perform routine maintenance. Even then they will concentrate on the removal of algae and pay little attention to the comings and goings of the fish around them.

While plecos generally ignore the other fish in an aquarium, this can not be said for the presence of other bottom dwellers. When it comes to their perceived domain, most bottom dwellers are highly territorial. It is exceedingly rare for bottom dwelling fish of any species to peacefully coexist with one another. They will vigorously defend their territory to the point of violence. Unless you have thoroughly researched the subject it is ill advisable to attempt to keep more than one bottom dweller in an aquarium.

As previously mentioned, all plecos are nocturnal. One of the first things they will do when they are introduced to a new environment is to seek out a place to call home. Supplying rock work or hollow aquarium décor is recommended in the set up of pretty much any community tank. This is of particular importance if you intend to keep nocturnal species. Providing these fish with a place they seek shelter in to avoid the harsh aquarium lighting during the day light hour will help them more easily adapt to their new surroundings. While this is not strictly necessary, it is recommended. Plecos will rest on the aquarium floor during the day in an unadorned aquarium.

Plecos are quite possibly the ultimate scavengers. They can survive in conditions where other fish would wither and die of starvation. Their consumption of both algae and decomposing matter left behind from the food particles missed by other fish is doubly beneficial in regards to aquarium maintenance and general upkeep. It is, however, inadvisable to assume that foraging will provide your plecos with enough nutrients to keep it healthy and fit. This is especially true if you own a larger member of the plecos family.

It is not uncommon for a plecos to learn to associate certain sounds with the availability of food. They will frequently rise to the top of the aquarium at feeding time and feed alongside their tank mates. If your particular plecos fails to make this intuitive leap, it is advisable to incorporate sinking wafers or pellets into feeding routine.  

Fruits and vegetables make an excellent dietary supplement. They will scarf down leafy veggies like spinach, cabbage and lettuce without hesitation. Skewering little chucks of cucumber, broccoli, squash, zucchini or cauliflower to a safety pin and letting it sink is like inviting your pleco to an all you can eat buffet. Veggies can be served raw or as cooked scraps right from your plate rather than tossing them in the garbage. Having driftwood in your aquarium is also recommended. Plecos love to chew on drift wood. This would seem to indicate that wood provides a needed source of fiber. Providing a good variety of vegetables to munch on will make your plecos less apt to devour the plants in your aquarium.

Armored catfish are built to survive. They will thrive in multitude of water conditions. PH levels can vary from slightly alkaline to slightly acidic. A pH range anywhere between 6.0 and 7.5 is perfectly acceptable. Water temperatures of 68-82 °F (20-28 degrees °C) is well within their comfort zone. Loricariids are a relatively long lived family. Given proper care and a well balanced diet you can expect your plecos to easily live in excess of 10 years.

A Word of Caution Pertaining to Plecos in an Aquarium: Make sure that your aquarium hood fits snuggly. It is also advisable not to fill your aquarium all the way up to the top. Plecos are accomplished jumpers. They are not strangers to breathing air. They routinely climb up the embankments of dried up streams and riverbeds in search of a new home in the dry season. They can and will escape from your aquarium if given the opportunity to do so.

Plecostomus Breeding

Plecos are not known to spawn in captivity. Attempts to commercially tank breed them have been unsuccessful. In the wild they dig pits in river beds to deposit their eggs into. A typical yield is approximately 300 eggs. Both parents guard the eggs until they hatch. Young fry feed off mucus on their parents’ bodies until the have matured enough to fend for themselves.

Most species that do not spawn in captivity are captured to support the thriving aquarium industry. This is typically not the case when it comes to armored catfish. Central and South America natives have turned the harvesting of plecos eggs into an industry all its own. The eggs are collected from drying streams and riverbeds and then sold to fish farms where they are hatched and raised for eventual resale. Many of the plecos for sale in fish stores were harvested just this way.

Plecostomus have, however, been successfully bred in Florida, Singapore, and Hong Kong. They are kept in large ponds with steep sides to prevent their escape. Plecos will dig borrows in the bottoms and banks of these ponds to deposit their eggs. The ponds are drained after the eggs hatch. Adults are relocated to other ponds for future spawning. The young are collected for sale within the fish hobby industry. Plecos are also bred and raised for export in fish hatcheries in Bangkok. 

Interesting Facts

The Hypostomus plecostomus or common algae eater’s original scientific designation was Plecostomus plecostomus. This taxonomical description referred to a single species quite obviously before scientists realized just how many individual species would be discovered that fit within what was later to be renamed the genus Hypostomus. It is plausible to assume that this is why the species name rather than the genus name became synonymous with this branch of the family Loricariidae.

Plecos are not Chinese Algae Eaters. Chinese Algae Eaters or sucking loaches are from the single genus Gyrinocheilus of the family Gyrinocheilidae indigenous to Southeast Asia.  Interestingly enough, Chinese Algae Eaters are not native to China at all. They come from Northern India and Central Thailand. “Chinese” most probably referred to their Asian origin at a time when Western Society was less conscience of the diversity of various Asian Cultures.

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