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    Species: Acanthicus hystrix

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    Species: Blue Eyed Panaque

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    Species: Glptoperichthys gibbiceps

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    Species: Liposarcus sp.

The Giant Loricariid catfish

Sooner or later every visitor to aquarium shops will encounter the suckermouth catfish, members of the Loricariidae. These fish are sold interchangeably as ‘algae eaters’ or ‘plecos’, in spite of being members of one of the largest families of fish. Loricariids range in lifestyles, temperament, and size, from the gentle inch and a half long Otocinclus affinis to the territorial giant Acanthicus. All these fish are fascinating to keep and watch, but many aquarists with an average sized community aquarium have been first startled, and then horrified, as their tiny algae eater grows – and grows – and grows… The evidence is there to be seen in many aquarium shops, where nearly any tank large enough for it to keep its head underwater contains a huge plec. Anyone who wants a giant catfish can buy a full-grown (or at least very large!) Hypostomus (plec) or Glyptoperichthys (leopard plec) for little more than a tenner, as the shops are unable to get rid of them fast enough. In spite of this, often in the same establishment, there will be a tank of endearing little plecs, a couple of inches long, making their way out of the shop one after another with aquarists who came in to get ‘something to eat the algae’.

If you are looking for a clean-up squad for your community tank, a pair of bristlenoses or a squad of Otocinclus will be continually at work, keeping the aquarium spick and span. On the other hand, if you have become enamoured of the giant loricariids, and are prepared to provide a home big enough to accommodate one or more, they are long-lived, hardy and often extraordinarily beautiful fish often that become ‘pets’ rather than animated room decorations.

The loricariids all come from South America, where the fluctuations of their home waters have led to a startling array of adaptations to make the most of what they have. In the rainy season, the fish have plenty to eat, and spawn either in burrows that they dig in the muddy banks or the substrate, or in naturally occurring holes and caves. When the dry season comes, life is somewhat harder. The floodplains dry out, and many are isolated in small oxygen-deficient pools. Others that remain in the main rivers find oxygen levels falling as the currents slow. To help with this all the big loricariids are capable of air breathing, with varying degrees of efficiency. Air is swallowed and absorbed through the walls of the intestine, with waste gases being discharged either through the gills or the anus. If the water levels fall too far in the pools the catfish do not have much time left, and use it as best they can by trying to walk to a new home. Their tough mailed skins mean that the fish do not dry out for an extended period of time, and they appear to be able to breathe air almost indefinitely. Using their strong pectoral fins, the fish can make it to a larger body of water, provided it is not too far away, although many succumb to drying out on burning sands with no water in sight. Those fish who have enough water to live in are still subjected to the attentions of the local populace, who take advantage of the reduced water depth to spear the catfish ready for cooking ‘in-the-shell’.

Given that they are capable of coping with their natural environment, it is unsurprising that the loricariids are among the easiest and most resilient fish available to the aquarist. Confusion still reigns when it comes to choosing a species by name. Not only are the ‘common’ names often common to more than one species, but the family is in a constant state of flux as far as scientific nomenclature goes. The ‘original’ plec, Hypostomus plecostomus, started its name career as Acipenser plecostomus in 1758. (The genus Acipenser now includes only the sturgeons, a group of fish who also have tough plated skin, although this is only a superficial resemblance). It was referred to as Plecostomus plecostomus by Gronovius in 1754, but eventually ended up as Hypostomus plecostomus. The original Hypostomus, Hypostomus guacari, was described by Lacepede in 1803, which actually turned out to be the same fish as our friend the ‘plec’. The much smaller bristlenose catfish, Ancistrus cirrhosus, started out as a Hypostomus before moving, eventually, to Ancistrus, while the sailfin plec, now Glyptoperichthys gibbiceps, started off as an Ancistrus before passing through Pterygoplichthys on its way to its current name! The upshot of all this is that even loricariid enthusiasts have an uphill task to know the latest names for everything. As if this was not enough, new species (or variants) are being imported regularly and simply assigned L-numbers instead of names, although some have later been properly described. Information about L number fish is sparse, and largely needs to be gathered from other enthusiasts or guessed from the attributes of other, similar fishes.

Fortunately, the giant loricariids all have similar requirements in terms of care. They are all vegetarians tending towards the omnivorous, and require a basic vegetable diet. This can be supplemented with occasional treats of frozen live foods (or live foods that can’t swim very well, such as bloodworm. There is very little point in feeding loricariids live daphnia or any active swimmers.) All vegetarians require far more bulk and produce far more waste than meat eaters, and the Loricariidae are no exception. A large loricariid catfish will eat a prodigious amount of food, and produce enough waste to overwhelm all but the most powerful and efficient of filters. As they all enjoy water currents and high oxygen levels, it is better to err on the side of larger rather than smaller when choosing a filter. Undergravel filters will not cope adequately, even if you are prepared to spend your life vacuuming the gravel, and a large external power filter is ideal. As the majority of loricariids tend towards the nocturnal, bright lighting will keep your fish inactive for most of the time. Many will happily be active in dimmer light, especially when bribed to do so by feeding. When choosing the tank, bear in mind that the loricariids are not particularly active, but still need to be able to turn round occasionally. Their armoured skins do not permit them to be very flexible. If you have a two foot long fish, it will have great trouble turning round in a foot wide tank, no matter how long the tank is. The fish will be happier in a three-foot square tank than in one that is six feet by one and a half. Height is also wasted, as they spend their lives on the bottom or attached to the glass, and will not cavort in midwater no matter how much of it there is. If the catfish is to be part of a community, care needs to be exercised. Although the catfish lurking at the bottom are often ignored by other fish, and are unappetising anyway, some fish may take grave exception to a catfish grazing the glass near their new clutch of eggs. Further, many of the large loricariids can be aggressive. Although Hypostomus is usually regarded as a peaceful large community fish, there are several recorded instances where these fish have become killers. Other species are even more likely to cause trouble. Acanthicus are very large and spiky, and although some literature (and keepers) claim them to be peaceful this is certainly not always the case. My own Acanthicus hystrix shows the most premeditated aggression I have ever seen in a fish. Not being a good swimmer, he has little chance of catching anything in midwater, so lurks patiently until he spots a fish swimming between him and the glass. At this point he erects his long and unpleasant interopercular spines and with a well-timed rush impales his unfortunate victim against the glass. After he has sawed backwards and forwards a few times, he retreats to allow the luckless recipient to float to the top. He succeeded in performing this manoeuvre three times before his ‘benefit of the doubt’ was withdrawn, and now lives in solitary splendour.

There are many large loricariid catfish that are suitable for a large aquarium, ranging from the cheap and easily found Hypostomus and Glyptopericthys to the exotic, beautiful and expensive Panaques and Acanthicus. If you want an ordinary plec, you will find it easy to acquire a large one at a reasonable price, but if you have set your heart on something more exotic you will probably need to buy a baby and raise it yourself. Remember that it will require a bigger tank sooner than you think!

Hypostomus sp

Although succeeding in identifying a loricariid as far as the genus level is an achievement for most retailers, not all little ‘plecs’ are Hypostomus plecostomus. A few days examining the large specimens in local shops will reveal species ranging from the dull brown to those with very beautiful markings and patterns. At present there are dozens of species of Hypostomus currently valid, and probably more to come from the ranks of the L-numbers. The fact that many change their appearance as they grow to maturity does not help the purchaser to identify his specimen. They can grow up to nearly two foot long, although many specimens reach only a foot. It seems likely that these are species differences, but since few people know what they have got it is difficult to prove one way or the other. Various spawning behaviours have been reported: specimens introduced to North America were documented as spawning by laying eggs on smooth rocks, while those raised in Florida fish farms prefer to spawn by digging burrows in the banks of their mud ponds. Hypostomus punctatus has been reported as spawning in a hole in a piece of bogwood, while an unidentified pair spawned in a PVC tube after a protracted and violent courtship. Since there is no reliable way of differentiating between the sexes, and few people will have the facilities to maintain a group, breeding in the aquarium is largely a matter of luck. Most are peaceful aquarium inhabitants, but some become rogue killers, and a few develop an unfortunate taste for the excretions from the sides of other fish, causing stress by continually trying to attach themselves to their tankmates’ flanks. They are hardy and tolerant fish, as evidenced by the large non-native population that has established itself in North America, and are unfussy about the pH and hardness of their water provided it is clean and well oxygenated.

Glyptoperichthys gibbiceps

The leopard pleco (or sometimes ‘red plec’) finally settled into the Glyptoperichthys genus in 1991, but has been a popular aquarium fish under various names for many years. These have a tendency to be territorial, and fights may occur if more than one is kept, although most are peaceful towards other fish. The leopard plec is capable of growing to 50cm, and appear to be slightly less hardy than Hypostomus species. They are nonetheless fairly resilient, and are a common occurrence in aquarium shops, both as juveniles and large ‘rejects’. These fish are spawned in captivity for the aquarium trade in Malaysia, both by artificial inducement and naturally, in mud ponds where they dig out spawning burrows in the banks.

Liposarcus sp

Until the genus Liposarcus was recently rejuvenated, both Liposarcus anisitsi, the Snow King, and Liposarcus multiradiatus, the sailfin plec, shared the Pterygoplichthys genus with Glyptoperichthys gibbiceps. Both these species are usually peaceful aquarium inhabitants, but grow to a very large size and have so far only been spawned in ponds. The Snow King, which reaches a length of well over two feet, builds a spawning burrow in the soft mud banks or substrate, or in vegetation. The fish appears to reside in its burrow even outside the spawning season, and has been photographed in the dry season sitting high and dry in its burrow above the receding water level. L. multiradiatus is reported to spawn up to1000 eggs in a burrow at a water depth of around two feet. These fish are both notable for their large dorsal fins, and are generally peaceful aquarium inhabitants.


This genus is unusual in encompassing both very small and large fish. For those who do not want an immense tank, Panaque gnomus grows to only 3 inches, while P. maccus reaches 31/2 inches. P. maccus, at least, is currently being marketed under the name of ‘dwarf clown pleco’. Panaques can be differentiated from Peckoltias (the clown plecos) by their spoon-shaped teeth, although it is likely that some of the Panaques will be reassigned in the future. Several panaques appear to fall into the giant class, although many of the larger specimens have simply been slotted into the L number list. A fish which appears to be the Royal Panaque, P. nigrolineatus, measured two feet, although the official maximum length is just under a foot. This is a very striking fish in its juvenile colouration, when it is grey with black horizontal stripes. In some specimens in aquaria the colouring fades to a uniform grey colour as the fish ages, although large specimens retaining their striking colour have been caught. Many of these fish have arrived as imports in a state of advanced starvation, so it is important to check the belly before buying a Royal Panaque. A fish with a concave stomach will probably never recover, even with good feeding later. They prefer slightly acid water, and are sensitive to high concentrations of nitrates, so regular water changes are essential. Although usually peaceful towards other fishes, adults can be extremely territorial towards members of its own species. Panaque suttoni, the blue-eyed panaque, is recorded up to a foot long. Sadly this may be irrelevant for today’s readers, as the status of this fish in the wild state is extremely dubious, and it has never been bred in captivity. Several other panaques in the L-numbers are likely to prove to be new species, although others are probably variants of P. nigrolineatus.

Acanthicus sp

Acanthicus currently comprises two species, A. hystrix and A. adonis. A. hystrix has been recorded at over 80cm, while a specimen of adonis measured over a metre. Both are very striking fish, being covered with so many ornate spines they resemble living sculptures. A. hystrix is jet black, while adonis is spotted with white, at least while juvenile. Acanthicus species are described as community fish in some popular aquarium literature, but really should not be considered except on their own. Small specimens may settle in, but the fish get nastier as they get older, and have an impressive armament to enable them to vent their aggression. Not only are they so spiky that even picking up one that is behaving itself can draw blood, but they are equipped with a set of interopercular spines capable of serious damage (as described previously!). Acanthicus prefer soft acidic water, but are very robust fish. Their spawning is not documented, but it has been suggested that they may be migratory.

This article has been kindly provided by Kathy Jinkings and cannot be reproduced without her permission.

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