Article © Julian Dignall, uploaded May 01, 1999.

Royal Plecos are truly magnificent show fish. It is often written that their striking juvenile colours fade with age, but I've seen 14" adults that puts paid to that theory. Colouration aside it is probably their unusual shape and utterly graceless movement - akin to a swimming rock - that endear them to many aquarists not usually interested in secretive catfish. Indeed secrecy is the fishes main drawback. Once settled the fish will make occasional forays for food and this bravery increases with age but youngsters however can be considered nocturnal. They tend to cling to their beloved shady refuge for most of the day, movement only precipitated by intrusion of another fish into this sanctuary.

The Royal Pleco's wide geographical range also gives us some interesting colour variations which may someday be described as further species. There is a Brazilian gold stripe variety with a black background colouration, the shade of green ranges from olive to near blue, and the amount of black background colouration in relation to the stripes varies greatly. Some individuals have striped pectoral and pelvic fins, others are plain. Some sport entirely clear caudal fins, others have a clear half moon shape. In all these variations the distinctive red eye doesn't remain a constant either.

Close-up of teeth

All members of the genus Panaque have very distinctive teeth. The underside of the sucker mouth is quartered and on each quarter (or ramus) lies a slanted row of 6 - 8 spoon shaped teeth. The four rows of teeth are slanted in such a way around the mouth as to give the appearance of a rhombus with the mouth at the centre. These teeth are put to good effect when rasping algae from all surfaces, so much so that they will soon scratch plexi-glass tanks and you should keep an eye on the silicon at the corners of glass tanks. Whilst moving a 6" P. nigrolineatus, I kept it in a large polystyrene shipping box. Alarmed by a squeaky scratching noise coming from the box, I went over to investigate, but the noise stopped. I repeated this, rather comically, and at every approach the noise, again, stopped. Eventually, by standing very still over the box, I discovered the noise was the Royal Pleco grazing from the polystyrene base!

Although primarily vegetarian these fish will also take fish meat from time to time. Certainly mine would not shy away from the occasional frozen prawn, but the bulk of their diet was vegetable scraps taken from the kitchen, then attached to a rock near the fishes chosen refuge.

On the topic of feeding, it is quite common to find young Royal Plecos offered for sale in a terribly undernourished state; they require dedicated attention should you decide to purchase them. This can be achieved by quarantining them until they are feeding regularly and their body fats are restored. This is best accomplished in a bare tank - unpopulated except for the patient - and it should include a large piece of bogwood for refuge. Heavy filtration, alongside frequent feeding and water changes should be utilized to bring the fish round. Irrespective of the state of the fishes belly, individuals offered for sale with sunken yes almost invariably do not respond to this treatment and seem to be "too far gone" to be saved.

That said, good retailers know how to look after these fishes as soon as they get them and, assuming you do the same, these are plecos that live for many years. While they are not an inconsiderable investment, they really are great showpiece fishes and if you can tolerate the mess they make as being part of the challenge, then you will have yourself an excellent fish to look after.

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	Panaque nigrolineatus  (Peters, 1877)
Common Names	L190, Royal Pleco Rødøjet Kongesugemalle (Denmark), Schwarzlinien-Harnischwels (Germany), Stribet Sugemalle (Denmark)
Type Locality	Guárico River at Calabozo, Apure River drainage, Guárico State, Venezuela.
Synonym(s)	Chaetostomus nigrolineatus
Pronunciation	pan ah KAY. - nih GRO lin e AT us
Etymology	The generic epithet "panaque" is a Venezuelan common name for this fish. nigro = black; lineatus = lines or stripes alluding to the fishes black stripes.
Articles
Species Information
Size	430mm or 16.9" SL. Find near, nearer or same sized spp.
Identification	The genus Panaque is identified by the teeth, which are spoon-shaped. This means that the teeth are noticeably wider at the tip than at the base. Other loricariidae have teeth that are similar width all the way from one end to the other. A second distinguishing feature is the lack of a buccal papilla, which is a "flap of skin" on the inside of the mouth. See pictures in this PDF on Pterygoplichthys. These fish are imported in all sizes and in a number of colour forms. Interestingly the colour of the eye varies from bright orange to dull red. Although described from Venezuelan material, the colour forms that have given rise to L027 are from different locations such as the Rio Tocantins, Xingú and Tapajos, Brazil. It appears that the juveniles of Brazilian populations have solid or plain as opposed to barred caudal fin rays. So, a juvenile with barred caudal fin rays is from Colombian or Venezuelan stock.
Sexing	Undocumented, although with most ancistrine plecos the genital papilla of the female is round and blunt, that of the male by comparison is smaller and pointed. It is not known at what size this method of sexing can be used on Royal Plecos.
Habitat Information
Distribution	South America: Orinoco and southern middle and lower Amazon River tributaries. Amazon, Lower Amazon (click on these areas to find other species found there) Amazon, Middle Amazon (Solimoes) (click on these areas to find other species found there) Orinoco (click on these areas to find other species found there) Orinoco, Middle Orinoco, Apure, Guarico (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 2020.
pH	6.5 - 7.5
Temperature	22.0-30.0°C or 71.6-86°F (Show species within this range)
Husbandry Information
Feeding	Classic ''pleco diet'' of greens. Can be acclimatized onto most vegetables; tinned peas seem a favourite. The fish also appear to eat bogwood. Some prepared foods should also be offered to supplement this diet. User data.
Furniture	Bogwood is essential - both for dietary reasons and because it seems to be the Royal Pleco's preferred hide-out - although any suitably sized dark refuge will be utilized. When larger, Royal Plecos will re-arrange the tank to their own liking; ensure rocks are well secured and cannot be toppled against the glass.
Compatibility	Territorial with conspecifics and other similarly sized catfish although otherwise peaceful with smaller fish. This fish can be a fussy feeder and only once it is feeding well should be mixed with large, boisterous fish.
Suggested Tankmates	Most community fish, this fish is very secretive and so you will want more active fish around to provide something to watch.
Breeding	No published information exists, but I have heard that the fish has been spawned in captivity using some form of tube in a large tank (approx. 125 US Gallons). A false dry season of two weeks (low, warm, still water) was used. Then the tank was topped off with cooler rainwater (refilling about 80%). Lots of meaty and veggie foods were offered. The pair spawned within days.
Breeding Reports	There is no breeding report.
Further Information
Reference	Monatsberichte der Königlichen Preussischen Akademie der Wissenschaften zu Berlin 1877, pp 471, Unnumbered pl. following p. 556.
Registered Keepers	There are 322 registered keepers, view all "my cats" data.
Wishlists	Love this species? Click the heart to add it to your wish list. There are 6 wishes to keep this species, see who wants what.
Spotters	Spotted this species somewhere? Click the binoculars! There are 67 records of this fish being seen, view them all.
Forum BBCode
	Search for P. nigrolineatus
	Look up P. nigrolineatus on AquaticRepublic.com
	Look up P. nigrolineatus on Fishbase
	Look up P. nigrolineatus on Encyclopedia of Life
	Look up P. nigrolineatus on Global Biodiversity Information Facility
	LFS label creator
Last Update	2022 Jan 19 09:58 (species record created: 1999 May 01 11:22)

Back to Catfish of the Month index.