10 Best Rated Aquarium Power Filters

Best Rated Aquarium Power Filters in 2023

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Common Plecostomus

Detailed research paper about the common aquarium fish Hypostomus plecostomus

Glossary

apomorphy - a derived characteristic

benthic - associated with the bottom

ctenoid - elasmoid scale; found in many Teleosts; comb-like
margin

cycloid - elasmoid scale; found in many Teleosts; circular

dioecious - male and female reproductive organs
borne on separate individuals of the
same species

ganoid - scales found in Cladistia and Chondrostei;
usually rhomboid in shape

heterocercal - lobes on tail of fish are asymmetrical

homocercal - lobes on tail of fish are symmetrical

physoclistous - term for a swim bladder lacking a
pneumatic duct

physostomous - term for a swim bladder with a pneumatic duct

placoid - scale type found in sharks

pleisiomorphy - a primitive characteristic

pneumatic duct - a tube linking the digestive
tract to the swim bladder

protrusible - overhanging; jutting out

synapomorphy - a shared derived characteristic

The world's aquatic environments are home to a fantastically varied number of species, including over 25,000 species of fishes. A fish is defined as an aquatic vertebrate with gills, and limbs in the shape of fins. This definition applies in the vast majority of fishes, though there are some exceptions. Of these 25,000 species, roughly 58% reside in marine environments, and 42% make their home in freshwater. This is unique in a sense, because freshwater environments make up only .01% of the Earth's total water volume, a stark contrast to the 97% that is the Global Ocean. Hypostomus plecostomus is only one of a number of fishes generally referred to in layman's terms as the Common Pleco, but this particular species is responsible for the origin of the name.

H. plecostomus was first named by Linnaeus in 1758. The species has been renamed a number of times since then, the last being Plecostomus resiliencies by Bleecker in 1864, however the Common Pleco remains primarily known as H. plecostomus.

Phylogeny and Taxonomy

All organisms fall into a hierarchy of classification, beginning with their kingdom and proceeding down the ladder, becoming more and more defined with each rung. All fishes belong to the kingdom Animalia, and the phylum Chordata. This classification narrows all organisms down to only those with nerve chords or notochords. This

encompasses all vertebrates such as amphibians, and birds, as well as hagfishes, tunicates, and lancelets. The subphylum Vertebrata omits those without backbones, or vertebral columns, such as the hagfishes, the lancelets, and the tunicates. The nerve chord and backbone, both pleisiomorphs, are retained in my organism. Next comes the Gnathostome classification. Vertebrates must be jawed in order to belong in this classification. Jaws evolved roughly 450 million years ago initially most likely to facilitate breathing. Secondarily, they became useful in catching prey. Jaws evolved alongside an internal skeleton, paired fins, and gill arches, as fishes underwent a large change. These adaptations allowed for quicker, more efficient movement. Specifically, the skeleton was thought to be primarily important in mineral storage, and only secondarily important in protection and swimming. Paired fins evolved through what is thought of as the Fin-Fold Hypothesis. This states that fins developed gradually from lateral folds that later became subdivided into controllable segments. After this, rows of fins developed. The intermediate fins later were lost, leaving paired fins in their stead. These pleisiomorphies are maintained in my species, as well as most other present-day fishes. Hypostomus plecostomus begins to differentiate from other vertebrate fishes at this next point in classification. The Common Pleco is in the Class Actinopterygii, the ray-finned fishes. This means that their fins are supported by fins rays rather than skeletal extensions. The character changes that come with this class also include a change to ganoid scales from placoid, and a heterocercal tail. In this class there are three subclasses: the Cladistia, the Chondrostei, and the Neopterygii. Cladistia include birchirs and reedfishes, Chondrostei are sturgeons and paddlefishes, and the Neopterygii include gars, bowfins, and Teleosts, the infraclass the which H. plecostomus belongs. The Teleosts are the classification of fishes that dominate waters in the here and now. This is largely due to improvements in respiration, buoyancy, feeding, and swimming. Euteleostei are another classification to which H. plecostomus belongs. Plecos are also Ostariophysians, a classification that is in part defined by the presence of a Weberian Complex. This is an auditory adaptation that allows for enhanced capabilities and is essentially a modified vertebrae. In addition, these fishes possess Schreckstoff and Schreckreaktion, which are alarm response systems. These allow the fish to react quickly and effectively to an awareness of danger. H. plecostomus is in the order Siluriformes, the order of the catfishes. Roughly 10% of fishes are catfishes. This order is distinct because many catfish lack scales, possess barbels, and have fin spines. These are traits which are all maintained in my species. H. plecostomus belongs to the family Loricariidae, which is distinct because these fish are adorned scutes and have sucker-like mouths. Both of these synapomorphs are retained in H. plecostomus.

Zoogeography

H. plecostomus is native to the coastal drainage areas of Guyana and Suriname, but has been introduced to a number of Asian countries; Malaysia, the Philippines, Vietnam, Sri Lanka, and Thailand, as well as the United States as a result of the aquarium trade. Its native zoogeographic realm is the freshwater portion of the Neotropics, which collectively includes Central and South America as well as the Caribbean. This region is characterized by warm temperatures and long hours of sun as well as a lack of minnows. Due to their introduction, they are now subject to living in the Nearctic and Oriental regions. The Nearctic region is a temperate environment with great fish diversity and a varying daylength. Many fishes found in this region are better adapted to living in cold water conditions. The Oriental region is home to minnows and catfish predominantly and is characterized by warm temperatures and high humidity. This is an environment that clearly would be conducive to an H. plecostomus, population, as it is with a number of other catfish.

Anatomy and Physiology

The suckermouth catfish has a number of adaptations that separate it from other species and allow it to survive. H. plecostomus has a protrusible upper jaw which allows it to achieve suction and feed off the bottom. If it weren't for this adaptation, the suckermouth catfish may have been forced to occupy an alternate niche which could greatly alter their survival odds, possible even leading to their extinction. The rows of scutes on the top half of the body and head keep it protected while it feeds on the bottom. The scutes aren't necessary on the belly, because H. plecostomus for the most part stays on the bottom. Due to this, its soft underbelly is protected from attack. In addition to this protective measure, the suckermouth catfish has spines which can be locked out to injure potential predators or threats. H. plecostomus also has a number of sensory systems. As mentioned before, they possess a Weberian apparatus as well as an alarm response system. Also present are barbels, which act as a type of feeler to aid in movement, and a lateral line system, which is useful in electrosensing. Electrosensing is helpful to fishes who participate in migrations and to sense other fishes in close proximity. Another adaption that is important is osmoregulation. H. plecostomus is a freshwater teleost, so it's hyperosmotic, meaning it has to maintain a level of salts higher than that of the surrounding water. To do this, it has developed a large kidney to make large quantities of dilute urine, the kidney reabsorbs salts that it could potentially lose, it doesn't drink water, and chloride cells are present on the gills to gain ions from the surrounding environment. Another adaptation is in the way they swim. This fish oscillates its' tail to get from place to place. The maximum size for this fish is estimated at roughly 600 mm. Male and female Plecos are distinguishable from each other because males have wider heads and thicker spines, which can resemble sideburns in some species. (Elson in "Catfish")

Life History

The Common Pleco's diet consists mainly of benthic algae and small, benthic crustaceans. H. plecostomus is a dioecious species that participate in external fertilization. The eggs are deposited on smooth rocks or in depressions, where they are then guarded by one or both parents. The young hatch after three to five days as small versions of the adults, with no larval stage to speak of, and are more or less ready for life in the world. The Common Pleco prefers to consume algae from benthic surfaces, as their sucker-like mouth would imply. H. plecostomus is generally earthen in color, as they are benthic fishes. This helps them to avoid predation.

Community Relationships

H. plecostomus is a primary consumer in its food web. It eats predominantly algae, but will also dine on small benthic crustaceans. It is not a predator, yet it is not often prey, due to its bony scutes and dorsal spine, both of which discourage predation. This species has a relatively low community impact, as stated by Courtenay et al. In the GMSFC article; "[H. plecostomus is] innocuous, occupying a niche which has minimum overlap with niches of native fish species."

Conservation Status

H. plecostomus is commercially utilized as an aquarium fish. It is popular in this role due to its feeding habits. Plecos help keep aquariums clean by consuming the algae that grows on the glass faces and sculptures that decorate tanks. This species has little to no value as a food source. There are diseases that affect the suckermouth catfish. These diseases are parasitic in nature and negatively influence survival rate. It is afflicted with velvet disease, skin flukes, and white spot disease.

Works Cited

"Catfish: Everything About Natural History..." Google Book Search 28 Apr 2020

Garilao, Cristina V. "Hypostomus plecostomus: Suckermouth Catfish." Fishbase. (2005) 20 Apr 2020.

Gulf States Marine Fisheries Commission. "Hypostomus plecostomus." (2005). 24 Apr 2020.

Lundberg, John G., and Friel, John P. "Siluriformes." Tree of Life Web Project. (2003). 24 Apr 2020.

M. McGrouther. Australian Museum Online. "About Fishes." (2020). 29 Apr 2020