Author: Darren Stevens
First published in Aquarium World August 2011

Contrary to popular belief, red spots, gold spots, and common plecos are not types of Hypostomus as many people believe, but they are all types of sailfin plecos or Pterygoplichthys. Hypostomus species are relatively rarely imported. The confusion arises from the fact that the original ‘common’ plecos imported into the hobby in the 1960’s were species of Hypostomus. From the 1980’s the commonly imported plecos were all types of sailfin plecos or Pterygoplichthys. These two groups are easy to tell apart. As their names suggests sailfin plecos (common plecos, red spots, and gold spots) have an impressive broad-based dorsal (top) fin with 10–14 fin rays (+1 hard spine at the front) while Hypostomus species have a shorter dorsal fin base and 7–8 fin rays (+1 spine).

There are currently 138 scientifically described Hypostomus species making it the largest pleco group. The name Hypostomus comes from the Greek words ‘hypo’ meaning under and ‘stoma’ meaning mouth, in reference to the mouth being under the head (as is the case for all plecos).

Hypostomus species are widespread through South America from Venezuela to Argentina where they are generally found in slow flowing lowland waterways and lakes, often associated with submerged wood. These plecos are hardy, adaptable, and generally peaceful. However, most species will grow from 20 to 40 cm making them too big for smaller aquaria. Larger specimens can be territorial and aggressive towards other plecos, and need good filtration as they produce a large amount of waste. As they are wild caught, they are relatively expensive.

With so many Hypostomus species it is not surprising that their diet varies significantly from specialised wood eaters, to aufwuchs (essentially algal biofilm) grazers, to omnivores. Most species do well on a largely vegetarian diet of pleco algae wafers, veggies (courgettes, cucumber, silverbeet, shelled peas, etc.), and smaller quantities of high protein foods (shrimp pellets, shrimps, fish, blood worms, etc.). TheHypostomus cochliodon group (see below) are specialised wood eaters and wood is an essential part of their diet.

Most Hypostomus species have not been bred in aquaria. For many species this would be difficult to achieve as in the wild males burrow into muddy riverbanks to lay and brood their eggs. The followingHypostomus species are likely to be found in New Zealand.

The Hypostomus cochliodon group.

This group contains 16 very similar scientifically named species which were previously placed in the genus Cochliodon. We get a few of these species in New Zealand and they are variously marketed as bruno, Cochliodon, rusty, scarlet, or velvet plecos. Most species in this group have highly specialised spoon shaped teeth that enable them to chisel wood (and to scrape algae). As with the unrelatedPanaques, wood is regarded as an essential part of their diet. These plecos are difficult to identify and the following identifications should be regarded as tentative.

Cochliodon pleco (Hypostomus cochliodon L310, LDA7)

The Cochliodon pleco is a relatively large (to 23 cm standard length, SL) rusty brown pleco often with a wide tan stripe on the upper half of the body. Other individuals lack the stripe and are uniformly dark brown. Cochliodon plecos are found in Paraguay and middle Paraná River basins. They are suited to larger tanks with pH’s of 6.3–7.2 and cooler temperatures of 21–24ºC.

Spotted Cochliodon (Hypostomus cf. cochliodon, L050)

The spotted cochliodon pleco is a relatively large (to 18 cm standard length, SL) rusty brown brown pleco similar to H. cochliodon but covered with broadly spaced black dots. Spotted Cochliodons are found in Rios Tocantins and Lageado. They are suited to larger tanks with pH’s of 6.5–7.2 and cooler temperatures of 22–25ºC.

Blue eyed redfin pleco (Hypostomus soniae, L137)

The blue eyed redfin pleco is a relatively large (to 30 cm standard length, SL) rusty brown pleco with a broad tan markings on the upper half of the body, and as its name suggests pale blue eyes. Blue eyed redfin plecos are found in temporary pools on riversides of Rio Tapajós, Brazil. They are suited to larger tanks with pH’s of 6.0–7.5 and temperatures of 24–28ºC.

Another Hypostomus species that has occasionally been imported is the Honeycomb pleco. It is not a member of the Hypostomus cochliodon group and does not need wood in its diet.

Honeycomb pleco (Hypostomus faveolus, L037)

The Honeycomb pleco is a relatively large (to 21 cm standard length, SL) attractive dark brown pleco covered with pale brown spots separated by a thin margin giving a honeycombed appearance. They are found in rapids through to slow flowing rivers of the Upper Rio Araguaia, Rio Tocantins and upper Rio Xingu basins in Brazil. They are suited to larger tanks with pH’s of 5.0–7.0 and temperatures of 23–27ºC.

I would like to thank Krazy Geoff for his comments and improvements on earlier versions of this article, and Chris Down’s for allowing me to photograph his rustys.

References.
Planet catfish (www.planetcatfish.com)
ScotCat (www.scotcat.com)
Jonathan Armbrusters Loricariidae website
(http://www.auburn.edu/academic/science math/res_area/ loricariid/fish_key/lorhome/index.html)
Seidel, I. (2008). Back to nature guide to L-Catfishes. Fohrman Aquaristik AB, Sweden. 208 p.
Armbruster, J. W. (2003). The species of the Hypostomus cochliodon group (Siluriformes: Loricariidae).Zootaxa 249: 1–60.
Armbruster, J. W. (2005). Hypostomus macushi, a new species of the Hypostomus cochliodon group (Siluriformes: Loricariidae) from Guyana. Zootaxa 920: 1–12.
Hollanda Carvalho, P.; Weber, C. (2004). Five new species of the Hypostomus cochliodon group (Siluriformes: Loricariidae) from the middle and lower Amazon System. Revue Suisse de Zoologie 111:953–978.

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