Article © Julian Dignall, uploaded April 29, 2024.

If you don’t know anything about a fish, what can you tell by just looking at it? In the case of a pleco, it is often quite a lot. Some are generalists, but most have one or more specialisms such as what they eat or a particular biotope and how they live in it.

In the case of Lasiancistrus, we see flat (vertically compressed) species with showy caudal fins and a degree of sexual dimorphism mostly in the head shape. In comparison to the well known Ancistrus they have longer caudal fins, are a little slenderer and do not have the head tentacles seen in male Ancistrus as they mature. However, they have average suckermouths, with average dentition and are omnivorous generalists. Most prefer stone over wood, most are straightforward to keep in pH 6-7.5. Maxing out at around 1200mm SL, they do not challenge the aquarist to provide big tanks or particularly heavy filtration. Just like Ancistrus, groups can be kept and hierarchies will form with squabbles that don’t usually escalate into injury for the sparring fish.

L. heteracanthus is one of the most encountered species but it is not a common fish to see. As such, it’s useful to know what might be sold as this species or indeed under a common name that gets confused – this is because a number of species of Lasiancistrus share a similar caudal fin colouration. In these species, the lower lobe of the caudal fin is coloured or patterned, and the top half is not. So, let’s look at these fishes too.

L302 is from the Rio Nhamundá, Brazil in Brazil, it is not commonly seen and does not have a red colour in the caudal.

L. scolymus from the Mato Gross do Sul, Brazil has colour in caudal fin but also has tiny “starlight” spots much smaller than those seen in L. heteracanthus.

L033 from the Rio Araguaia, in Pará State Brazil is an option when you’re looking at ID but the caudal is darker reddish brown – as the fish grows the spots get smaller and the caudal fin patterning fades.

L178 from the Rio Tocantins in Brazil is really close except it has fine spots and a flash of red the upper caudal fin lobe too.

L228 comes from the Javary river which joins the Amazon main channel at Benjamin Constant – as such it will usually be exported out of Leticia and then globally via Bogota in Colombia. It is the hardest to tell apart from L. heteracanthus – main visual points are an orange eye and spots in the orange / red lower caudal fin lobe. As it’s also close geographically, one wonders if this is perhaps the same species.

L365 is the Tapajos one, no spots and only a glimmer of colour in the caudal.

L479 is from the Madeira system and is close to L. scolymus. L. heteracanthus is the species typically exported out of Iquitos, Peru via Lima to the world – an export mainstay route of the neotropical ornamental fish trade and as such means this is a species that is, at least, found for sale from time to time.

Care in the aquarium is straightforward. Clean water, regular feeding with most sinking foods and anything other then hyperactive or boisterous fishes will work. A group of these fishes takes the experience to another level. Then you being to see them showing off to each other, colouring or fattening up and generally behaving more naturally than if kept in ones or twos.

Lasiancistrus generally, and this species specifically, are excellent medium sized plecos that should not be overlooked. I’ve always liked them, and, I suspect, always will.

Copyright information for the images used in this article can be found on the species' full Cat-eLog page.

Cat-eLog Data Sheet
Scientific Name	Lasiancistrus heteracanthus  (Günther, 1869)
Common Name
Type Locality	Upper Amazon River basin, Peru.
Synonym(s)	Chaetostomus heteracanthus
Pronunciation	LASS ee an SISS truss
Etymology	Greek, lasios, -a, -on = hairy + Greek, agkistron = hook
Articles	- CotM 2024 April
Species Information
Size	153mm or 6" SL. Find near, nearer or same sized spp.
Identification	Adult Lasiancistrus can be separated from all other loricariids by the presence of whisker-like odontodes on the cheeks. In addition, they have evertible cheek odontodes; three rows of plates on the caudal peduncle; and a modified, bar-shaped opercle. The caudal fin is slightly emarginate to forked, with the lower lobe longer than upper. Nuptial males have tentacules on the pectoral-fin spines longer than their associated odontodes; and transluscent tentacules on the snout that have odontodes associated with them. Nuptial males lack hypertrophied odontodes on top of the head and lack long, bristle-like odontodes on the leading edge of the pectoral-fin spine.
Habitat Information
Distribution	South America: Marañon River basin, Peru. Amazon, Upper Amazon, Marañón (click on these areas to find other species found there) Log in to view data on a map.
IUCN Red List Category	Least Concern, range map and more is available on the IUCN species page. Last assessed 2014.
Husbandry Information
Breeding	Unreported.
Breeding Reports	There is no breeding report.
Further Information
Reference	Proceedings of the Zoological Society of London 1869 (pt 2), pp 425, Figs. 3-4.
Registered Keepers	There are 15 registered keepers, view all "my cats" data.
Wishlists	Love this species? Click the heart to add it to your wish list. There are 2 wishes to keep this species, see who wants what.
Spotters	Spotted this species somewhere? Click the binoculars! There are 7 records of this fish being seen, view them all.
Forum BBCode
	Search for L. heteracanthus
	Look up L. heteracanthus on AquaticRepublic.com
	Look up L. heteracanthus on Fishbase
	Look up L. heteracanthus on Encyclopedia of Life
	Look up L. heteracanthus on Global Biodiversity Information Facility
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Last Update	2020 Sep 28 07:18 (species record created: 2024 Apr 29 13:00)

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