Royal Plecos

Author: Mark Denaro

Known for their striking colors and bold patterns, royal plecos are fantastic fish for larger aquariums.

The genus Panaque includes a number of species that are sought after by aquarium hobbyists. These range from the clown pleco P. maccus to the blue-eyed pleco P. suttonorum, which was previously thought to be extinct in the wild but is now being imported again at very high prices. Of particular interest to aquarists are P. nigrolineatus and several related species collectively referred to as royal plecos. These large, boldly patterned fish are quite popular in the hobby, and most of the information presented about royal plecos is applicable to the other members of the genus Panaque as well.

A Regal Lineup

As with humans, the vast majority of plecos are neither regal nor royal, so consequently, you may be wondering which plecos are royal. The fish considered to be the original royal pleco, P. nigrolineatus, has been imported since the early 1980s—before the explosion in popularity and availability of loricariid catfish—so it is a venerable, familiar species to long-term hobbyists. It was originally described based on specimens collected in Venezuela and Colombia, but closely related forms are wide-ranging with many of the best-known L numbers (loricariids that have not yet been given a scientific name are given an “L” designation) coming from eastern Brazil.

P. nigrolineatus

P. nigrolineatus is sold as L27a or L190. L27, the gold-line royal pleco from the Rio TapajÓs, previously thought to be a regional variant of P. nigrolineatus, was described as P. armbrusteri in 2010. The royal plecos from the Rio Tocantins and Rio XingÚ should be referred to as P. cf armbrusteri at this point, indicating that they seem to be a color form of P. armbrusteri. Subsequent study may determine that these are valid species in their own rights. They are both sold as L27b in the trade, so it is important to learn the collection location prior to purchase if you want to know for sure which one you are getting.

The thunder line royal pleco is sometimes sold as L27 or L27c and may be the most strongly patterned and visually appealing of the royal plecos. The Colombian L191 is similar in appearance to the previous two species and has not yet been scientifically described. It is typically imported as a juvenile, at which time it sports a white band in the caudal fin, leading to one of its common names, the white-tailed royal pleco. It is also sometimes called the dull-eyed royal pleco. L330, another Colombian species, is referred to as the spotted royal pleco or the watermelon pleco, and is generally known as P. cf. nigrolineatus.

P. titan

The Peruvian royal pleco P. titan, known as L418, the Peruvian green royal pleco, or the shampupa pleco, has a juvenile pattern very similar to that of L191, but the adult is much more drably colored. It inhabits the Napo River drainage in Peru and Ecuador. The papa royal pleco, L90, also hails from Peru. It develops very long extensions from the top and bottom of the caudal fin, making it one of the more striking royal plecos. The third member of the Peruvian contingent is the black royal pleco P. schaeferi or L203, which also has a white area in the caudal fin in juveniles but a less distinct pattern on the body than the other royals. It has the distinction of being the largest member of this group, growing to approximately 24 inches in length, which gives rise to its other common name of Volkswagen pleco, while the other species and variants generally max out in the 15- to 16-inch range.

Feeding Habits

Royal plecos and other Panaque species have evolved to feed on submerged wood and the various organisms and detritus present on the wood. Their teeth are shaped almost like a woodworker’s tool or can be described as spoon-shaped. They are larger at the tip than at the base. The dentition, combined with the strong maxillary (jaw) muscles enables these fish to scrape wood in the wild and in the aquarium.

On the surface, it seems very simple to say that these fish eat wood as a large part of their diet. The reality, though, is that they are feeding on the wood and everything that comes with it, including bacteria and fungi that are working to break it down. These play a key role in the diet and should not be overlooked. They may also feed on plant and other detritus that is present on the surface of the wood.

These factors should all be considered when planning a menu for these fish. Driftwood should certainly be present and available, and several different types of driftwood should be included in the aquarium as some are more easily ingested than others. In addition, a broad range of other foods should be offered. Royal plecos will eat algae-based foods such as wafers and flakes but will also accept meatier foods in the form of pellets, tablets, wafers, frozen, and flakes. Offering a varied diet is one of the real keys to success over the long haul with royal plecos.


Because the fish will rasp any wood present in the aquarium and need that in their diet, driftwood should be the primary focus of the aquascape for royal plecos. They will almost always prefer to hang out on or under driftwood, so the addition of lots of wood is beneficial to the fish and should be aesthetically pleasing to the aquarist.

One issue to beware of when creating a habitat that includes a lot of wood is the creation of dead zones in the tank where there is little or no water flow. Because these are fish that grow large and produce copious amounts of waste, excellent filtration is a must. High flow, efficient power filtration is best. Supplementing the filtration with the addition of one or more powerheads will help to avoid any dead zones if they are carefully positioned. Powerheads will also help to keep waste and detritus in suspension long enough for the power filters to remove them.

Creating a jumble of driftwood that represents a point in a river where fallen trees have collected will help to provide hiding spots for more than one fish if you intend to keep a group. The royals don’t tend to hang out in open-ended caves like their smaller brethren Hypancistrus spp., so the addition of clay caves is not necessary. They have a bad habit of rasping holes in plant leaves so plants should probably be left out. Similarly, they will rasp holes in plastic or silk plants too, and their ingestion of these pieces can lead to intestinal blockages and other issues, so artificial plants should also be avoided.

Setting Up a Royal Pleco Tank

By not using plants, it is possible to use lower lighting levels, which will make the plecos more comfortable and therefore more active, so you’ll get more enjoyment from watching the tank. Despite the fact that many of the royals come from soft, acidic water, I have universally found that they do better in basic, moderately hard water in the aquarium.

Water Requirements

If your water source is soft and acidic, you can buffer the pH and add to the hardness by adding a mesh bag filled with aragonite to one of your filters. If this doesn’t work in your power filters, you can always add a box filter filled with aragonite and hide that somewhere in a rear corner behind some driftwood. Depending on the type of driftwood you are using, the tannins released may cause the pH of the tank water to drop precipitously when lots of wood is used, so adding some aragonite is probably a good idea in general for this setup. The problem of tannins lowering the pH can actually get worse over time because their scraping of the wood will continuously expose new layers of driftwood to the tank water, so the wood will continue to release tannins.

Regular partial water changes are a must for these fish: 25-percent weekly water changes along with vacuuming the substrate and siphoning out any debris that may be stuck on the wood is a good basic maintenance plan. Temperatures should be in the upper 70s to low 80s F.

Tank Size

Due to their large adult size, the ideal aquarium for royal plecos will be at least 125 gallons and preferably larger. I prefer to use tanks that are at a minimum 24 inches from front to back so that even full-grown fish will have room to turn around. That said, many royal plecos can be purchased at sizes of 2 to 4 inches, so it is possible to start them out in tanks as small as 40 gallons. The breeder tanks that are 18 inches front to back work well for these smaller specimens. If you do start with a smaller tank, remember the size that these fish can reach and be sure that you can adequately house them as they grow. It is not fair to the fish to keep it in a tank that is too small and in which it may barely be able to move.


Since these catfish have a low daytime activity level, adding some other fish to the tank will provide more movement and will add visual interest for the observer. Tankmates need to be matched well to complement the plecos, so give this some real thought prior to making a purchase. One factor to consider is the level in the water column that the potential tankmates inhabit. The plecos will spend their time on the substrate or on the driftwood and will occupy the lower levels of the aquarium, so think in terms of fish that will be active higher in the water rather than those that hug the substrate.

Adding other species that tend to hide a great deal will not add anything to the overall visual effect of the aquarium, so active species are preferred. Royal plecos and many other loricariids can be easy targets because they are relatively slow moving. Therefore it may seem obvious, but fish that have a tendency to nip fins should be avoided. Species that do best in brightly lit, heavily planted tanks are also poor candidates.


Assuming that the choice will be made from species that come from the same geographical areas, mid-sized to larger tetras are probably the best choices. Species that will work particularly well include the various Hemiodus and Chalceus species. These are peaceful, active fish that grow to 3 to 8 inches in length, making them well suited to the larger aquaria that should be used for the royals. Both of these genera are accomplished jumpers, so their tanks must be tightly covered.

Moenkhausia agnesae is harder to find but would make a wonderful addition to the royal pleco aquarium. This mid-water schooling tetra is deeper bodied than members of the two previous genera and is attractively patterned.

Other Characins

The various headstanders of the genera Abramites, Anostomus, and Chilodus are also good choices. Of these, Abramites hypselonotus, the marbled headstander, is a particular favorite of mine. Because plants should not have been included as part of the aquascape, various silver dollars are also potential tankmates. If you choose to add silver dollars, be careful to ensure that the plecos get enough food, as the silver dollars will relish the food fed to the plecos. Feeding the plecos at night after all the lights are out, including the room lights or just prior to turning out the room lights, can give them the upper hand in finding the algae and vegetable-based foods that the silver dollars might find more easily in brighter light. Obviously, your choices are not limited to these species but include most of the characins and related families.


A number of cichlids are suitable as well, but many of them may pose some difficulties at spawning time when they may attempt to keep the royals out of their territories and away from their eggs and fry. Still, as long as they are not particularly aggressive, things should work out okay and the royals may well get a free meal of eggs or wrigglers, as the parents may not be able to push them away.

One cichlid that works particularly well is the festivum Mesonauta festivus. It is peaceful and active up in the water column rather than near the substrate like most other cichlids. Angelfish also work well, with a preference for wild angels. Domesticated angels will spawn too frequently, and their territoriality at these times can be a nuisance. Wild angels are seasonal spawners and don’t spawn as readily as their tank-raised cousins, so they are a better choice. Wild angels also display more complex behavior than the average domesticated strain.

Predatory Fish

Another option will be to add predatory species so that each species can be fed specifically and the hobbyist will not need to be concerned about more active fish getting the lion’s share of the food intended for the royal plecos. While their inactive nature violates my previous advice, a group of leaf fish Monocirrhus polyacanthus would work very well in a setup such as this—but remember that leaf fish are very challenging and almost impossible to wean off a diet of small live fish.

A Royal Display

Next time you are trying to decide how to stock a large aquarium, be sure to consider adding a little pomp and circumstance to your life by trying your hand with some royal plecos. If you’re looking for something a little different from the typical community tank, this group will reward your decision with interesting patterns and behavior.

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