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From Pan-ack-ay to Pan-ack-zee, A Detailed Look at the Bizarre But Beautiful Panaque Catfishes

By Neale Monks

Panaque nigrolineatus

The catfishes of the genus Panaque are without a doubt my personal favorites. Their clumsy bodies and bright colors combine to make them the clowns of the Loricariid catfish family. Another big plus with Panaque is that its species span a range of sizes from three inches upwards, so that there truly is one for every aquarium. They aren't fussy about water chemistry, and will do as well with mbuna as they will with discus. Their overall hardiness contrasts with their flamboyant colors, and provided a few basic rules are adhered to, these fish are eminently suitable for even relatively inexperienced aquarists. That said, these aren't fish for the immature aquarium, and while the rules to keep Panaque aren't onerous, they're definitely non-negotiable!

Incidentally, there are several different ways to pronounce the word Panaque. The native name for these fish is pronounced as pan-a-kay, and that is presumably the 'correct' pronunciation, but it is common to hear the name also pronounced as pan-acky, pan-ack, or pana-koo-ee. The name itself means canoe eater, the explanation for which should become obvious shortly! 

Panaque biology

Most Loricariid catfish are omnivores that will eat both plant and animal matter depending on what's available. Many aquarists will have seen a supposedly vegetarian Pleco digging into the corpse of dead fish in the aquarium! Panaque are no exception, and eat a variety of foods in the wild and in the aquarium. What is exceptional about the genus is that Panaque species are able to add wood to their diet as well, something other Loricariid catfish cannot do. Researchers at Towson University, Maryland, have demonstrated that Panaque are not only able to supplement their diet with wood, but they are even able to thrive and grow when fed nothing else!

By studying specimens in the wild as well as in the lab, the researchers found out that Panaque are equipped with spoon-shaped teeth that help them to rasp away at wood. Wild specimens sometimes have stomachs filled with wood shavings (something that isn't always the case with aquarium specimens, of which more will be said later). The gut contains a variety of symbiotic bacteria, fungi, and protozoans that somehow break the wood shavings down into simpler carbon compounds that the fish can absorb and use. The precise mechanism of wood digestion is still unknown and an active area of research, but since the River Amazon is filled with decaying wood and nothing much eats it, the trick must be a very useful one. A lot of other fish are dependent on foods that vary in availability throughout the year, such as fruits and insect larvae, but because Panaque catfish can take advantage of the ever-abundant supply of wood when other foods are scarce, they can feed and grow all year round. Panaque certainly can get bigger than most other Loricariids, being stockier and heftier than other catfish of similar length. The largest species in the trade is Panaque nigrolineatus, but one as-yet undescribed species reaches no less than three feet in length!

One of the interesting observations made by the researchers concerned the stomach contents of wild fishes compared with aquarium specimens. As mentioned before, those of wild fish are often filled with wood shavings, but most of the dead specimens donated by aquarists had empty stomachs. Furthermore, aquarium specimens from Brazilian populations of Panaque nigrolineatus in particular had deposits of fat around the internal organs, something wild fish never had. Why were wild and aquarium fish so different? The obvious answer is that many Panaque in aquaria simply aren't given the wood they need to eat, on the assumption that like other Loricariids they are basically generalists. While Panaque will eat all kinds of things, wood really should be at the heart of their diet, and any aquarium containing these fish must also have plenty of wood upon which they can graze. The corollary to this is that they shouldn't be pampered too much and given fatty foods that they wouldn't eat in nature. Panaque certainly do enjoy prawns, mussels, and other meaty foods, and these may even be safe as the very occasional treat, but the staple diet has to be wood supplemented with crunchy vegetables such as carrots, zucchini, and sweet potato. In terms of commercially prepared foods, stick with those based on algae and vegetable protein rather than fishmeal. Algae wafers as well as Spirulina and Chlorella-based chips and pellets are ideal. 

Reproductive biology

Only the smaller Panaque catfishes have yet been spawned in the aquarium, and their breeding behavior appears to be essentially similar to that of other small Loricariids such as Ancistrus. But the larger Panaque haven't spawned in aquaria, and ichthyologists studying these fishes in the wild have gathered only a little information. Breeding appears to take place not in the areas of the river filled with wood where the catfish feed, but in rocky channels. Spawning takes place during the rainy season, when the water level starts to rise. The eggs are laid underneath large rocks and in riverside caves where the water is less turbulent, and each clutch contains several hundred rather large bright yellow eggs. Females become sexually mature at well below full size; specimens of Panaque nigrolineatus in the wild have been observed to be full of eggs at a mere eight inches in length, which is only about half their maximum size.

It is often said that mature Panaque can be sexed simply by looking at the development of the odontodes on the cheeks and pectoral fins. However, scientists working with Panaque have found that while mature males certainly have lots of odontodes, so too do sexually mature females filled with eggs. Bottom line: you can't reliably sex a Panaque just by looking at it.

Juvenile Panaque often have somewhat different coloration to their parents; juvenile Panaque nigrolineatus, for example, sport a large white patch across the tail fin. They are very active, rather omnivorous, and have less well-developed teeth than the adults. Wood appears to be a minor part of their diet, and will happily eat not just algae and vegetables but also bloodworms, shrimp, and other meaty foods. As they mature and their coloration turns into that of the adults, they become more territorial as well, perching on a favored piece of wood and driving off any conspecifics that come too close. It is at this time that they begin to seriously feed on wood, being now equipped with a full set of robust teeth like those of the adults. Juvenile Panaque grow quickly.

Aquarium conditions

As mentioned before, these are essentially hardy fish, provided their basic needs are met. Wood should obviously be in constant supply in the Panaque aquarium, but experiments in labs have suggested that the efficiency of wood digestion depends to some extent on water quality. If the nitrates are too high, these catfish can't digest the wood properly, and slowly starve if given nothing else to eat. Possibly the nitrates interfere with the metabolism of the microorganisms in the catfish's gut. Regardless, this does underline the fact that large and regular water changes are essential.

As well as improving water quality, water changes are a good time to siphon out the prodigious quantities of feces these fish produce. Most of this waste isn't particularly toxic, being largely wood chippings, but it is unsightly, and there's so much of it! A six-inch specimen produces about one-eighth of a cup per day. Expecting your filter to remove all of this is unrealistic, and siphoning the stuff out every day or two makes much more sense, and besides, it's great fertilizer for your houseplants!

Decor can be as simple or complex as you want. Hiding places are appreciated, but bear in mind these catfish can scrape away the varnish and paint from plastic and ceramic ornaments. In fact, plastic generally tends to get covered in tiny scratches, so these definitely aren't catfish for the acrylic aquarium! Wood and rocks are the best decorative materials, and any bogwood used will also be a source of food for these catfish as well. They enjoy digging, so while gravel may be cheaper and easier to clean, silver sand can also be used if you want to watch them forage in a more natural manner. An inch-deep bed of sand will be kept spotlessly clean as these catfish plough through it, spewing the sand out of their gills while hunting for bloodworms and other small morsels. It goes without saying that big specimens are very powerful fish, and the aquarium needs to be robustly put together, so don't balance heavy rocks precariously on top of one another -- these catfish will quickly pull them down!

Panaque cannot be easily kept in planted aquaria. Flexible plants like Vallisneria and Cabomba will simply get uprooted, and plants sturdy enough to support their weight, such as Anubias and Amazon swords, are simply eaten. The smaller species may be mixed with Java ferns and Java moss, but the larger species tend to pull these plants of the bogwood their attached to while feeding. Floating plants on the other hand are an excellent addition to the Panaque aquarium. Besides providing shade, floating plants invariably grow quickly and remove plenty of nitrates in the process, improving water quality. 

The royal Plecos

The most commonly traded Panaque species are those referred to collectively as 'royal Plecos.' These are all fairly big (around 12-18") and more or less similar to Panaque nigrolineatus, a fish found across the Amazon basin in Brazil, Colombia, and Venezuela. Panaque nigrolineatus is the 'standard' royal Pleco, and has a dark grey body covered in light grey stripes. Its eyes are red and its tail fin edged with gold. Juvenile fish are similar to adults except that they sport a large white patch that covers most of the tail fin. In some cases, the contrast between the light and dark stripes on the body declines as the fish mature, but this is certainly not always the case.

Panaque nigrolineatus, (Peters 1877), the royal Panaque. To 43 cm. pH range: 6.5 -- 7.5; dH range: 2 - 15 , tropical: South America: Orinoco and southern middle and lower Amazon River tributaries. Feeds on plants and wood/roots. http://fishbase.org/Summary/species Summary.php?ID=12216&genusname= Panaque&speciesname=nigrolineatus

Bigger PIX: The images in this table are linked to large (desktop size) copies. Click on "framed" images to go to the larger size.

Blue-eyed Plec  7/14/09
Hi Bob,
I noticed WWM lacked a Panaque cochliodon (formerly P. suttoni) on the relevant article, here:
Happened to come across a specimen at the Bolton Museum Aquarium in the north of England. As you know, their native habitat is smack-bang in the middle of Colombian drug country, so these fish have been absent from the hobby since the early 90s. Figured that even though this picture isn't great, it would at least furnish WWM with something showing the key characteristics. Velvety-black body, blue eyes, numerous odontodes on the cheeks and pectoral fins.
Cheers, Neale
<Thank you Neale. Will post w/ credit to you. BobF>  

Several distinct varieties of royal Pleco turn up in retailers' tanks as well. The watermelon Pleco (also known as L027a and L330) is perhaps the most similar to the standard royal Pleco, but the light grew stripes are instead broken up into short squiggles and blobs. The olive royal Pleco is also quite similar to Panaque nigrolineatus, but the overall color of the fish is greenish-grey and rather muted, hence the common name. It is often called L027b, but it may also be sold as the Rio Teles Pires royal Pleco, a reference to a river where it is found. Another variety named after a river is the Rio Tapaj--s royal Pleco, also known as the golden line royal Pleco, a brilliantly colored species marked with golden stripes against a brownish-black background. Instead of the white patch typical of juvenile Panaque nigrolineatus, the tail fins of juvenile Rio Tapaj--s royal Plecos sport a semi-transparent patch instead. The Rio Tocantins royal Pleco is different again, which as a juvenile has a silvery-grey body tone much lighter than that of the standard royal Pleco. Further differences include an orange rather than red eye and a black patch on the tail instead of a white one. This fish is sometimes called L027c, but more commonly the platinum royal Pleco. Juvenile Rio Xingu royal Plecos are just as distinctive, with broad reddish patches on their fins. As they mature, these colorful patches fade away, but this variety is still known as the red-fin royal Pleco to the hobby.

"A very undernourished Panaque sp.; not sure which one. Possibly L191, also known as the "Dull Eyed Plec". Gets to about 25 cm, eats wood and vegetables, plus a little animal protein (though like your marine lionfish, I've been told by scientists working on dead specimens from aquaria rather than the wild these often have fat around the body organs thanks to a too-rich diet)." NealeM.  

All the royal Plecos are similar in terms of care, with the one exception that the Rio Xingu royal Pleco prefers, like other Rio Xingu fish, water that is a little warmer than average (around 80ûF being ideal). They mix well with other fish, though they are territorial amongst themselves. Royal Plecos are often considered to be rather shy, but that isn't really true. Once settled in, these fish can become quite trusting and will forage about happily during the day. If regularly offered slices of tasty vegetables at the same time during the day, they will even learn to swim out in the open and wait for their meal! On the other hand, if they have to share a tank with boisterous fishes like cichlids, they will become much more reserved, and at best the aquarist will only glimpse them hidden away in their favored hiding place.



The Clown Plecos

At the other end of the size range are the dwarfs of the genus, in every way delightful, if rather retiring, fishes perfectly suited to the community aquarium. In general their care is similar to that of their larger relatives. Panaque maccus is the most common of these 'clown Plecos' to be imported, though doubtless there are other similar species that are periodically traded as well. It gets to about three inches in length, and is an attractively marked little catfish, with a woody brown body bearing transverse light brown bands. Also known as L104 and L162, Panaque maccus is unfortunately not the only catfish sold as the clown Pleco, as the name is sometimes applied rather indiscriminately to any small, brown, banded, catfish, including Peckoltia vittata (L015, also known as the candy-striped Pleco). But identifying these small species of Panaque isn't difficult if you get to see them from underneath: they have the same impressively large, spoon-shaped teeth as their bigger cousins!

For a while these smaller Panaque species were known among hobbyists as Panaqolus. The fish scientists didn't adopt this name though, and it has largely fallen out of use. But you may come across it in some books and web pages, so it's as well to be aware of it. 

The Blue-eyed Pleco

One catfish you're unlikely to encounter is the blue-eyed Pleco, Panaque cochliodon, sometimes referred to as Panaque suttoni in older aquarium books. This catfish was actually rather commonly traded during the 1980s. However, the only population of these catfish is in what are now rather lawless parts of Colombia, and for that reason fish exporters cannot collect them safely. They are now virtually never seen in the trade.



The blue-eyed Pleco is an impressive beast, with a velvety black body and brilliant blue eyes. It can change its color somewhat, and when stressed turns greenish-grey. Like other Panaque, its skin is rough, even bristly, but set against the black this gives it a very distinctive golden sheen under certain lights. In terms of care, it is identical to the royal Pleco, but one peculiarity is a predisposition to a Rickettsia-like bacterial infection. Should you be lucky enough to obtain a newly imported specimen, it should be quarantined and provided with optimal water conditions and plenty of the appropriate foods. Treating proactively with anti-bacterial medications may be useful, too.

Buying your Panaque

Panaque are hardy once settled in, but the first few weeks after import are critical. As a general rule, avoid any specimens that have hollow bellies and sunken eyes, as these are frequently too badly starved to be saved. If the fish simply looks a little thin, but the eyes are bulging out of the head and the fish otherwise seems active and healthy, then bringing the fish home and providing it with plenty of food should do the trick. Ideally though, find a retailer who knows about Panaque catfish and is keeping them in a tank with wood and vegetables constantly on offer.

Obviously make sure there's wood in the aquarium, but also provide some vegetables and algae or vegetable based catfish pellets. Cucumber skin and sliced zucchini appear to be irresistible delicacies, but other aquarists have had good results from things like spinach and tinned peas. Meaty treats, like bloodworms, can be offered as well, but sparingly. Panaque can be shy feeders, and at first should either be in a tank of their own or else mixed with fishes that will not compete with them over food. Neons and guppies would be fine, but another Pleco would not be such a good idea.

Final thoughts

Panaque are lovely catfish that combine good looks with interesting biology. While the author is lucky enough to have kept a clown Pleco, blue-eyed Pleco, and a royal Pleco over the years, he is especially grateful to have received plenty of information on these fishes from researchers working with them in the wild as well as in laboratories. My sincere thanks go to Hirofumi Nonogaki (University of Maryland Center of Marine Biotechnology), Jay Nelson (Towson University), and Don Stewart (State University of New York College of Environmental Science and Forestry). Unfortunately, the habitat Panaque prefer is under intense pressure from logging and other human activities. This makes it even more important that aquarists provide every specimen with the care and conditions they need.


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