Few catfish are as active as the long-barbeled members of the genus Pimelodus. There are 24 described species in this genus, nearly all being metallic silver fish with long barbels and black markings on slender bodies. Most attain lengths of about 6 to 10 inches.
Perhaps the most popular, Pimelodus pictus, at a maximum size of just 5 inches, is one of the smaller species in the genus. A school of healthy P. pictus at the aquarium shop will catch anyone’s eye. The elongated barbels, sometimes as long as the body of the fish, and polka-dotted tinfoil silver bodies racing around the aquarium while looking for fish food make a great display.
When the species was first discovered, it was given the trade name Pimelodus angelicus, and it is still sold as the angelicus catfish in some places. The name is somewhat confusing because of the African species Synodontis angelicus, which used to be much more rare in the hobby and is black with white spots. This confusion may have started as a deliberate marketing ploy to attract the attention of those who could not afford the Synodontis (which sold for hundreds of dollars) and wanted a substitute. To avoid further confusion between the two species, the common names “pictus cat,” “pim pictus” and “spotted pim” were suggested, and these are now used widely in the international aquarium trade.
In South America, catfish of the genus Pimelodus are widespread. They have evolved a keen sense of smell and taste that allows them to home in on potential food sources from a distance. Also, they do not limit themselves to live crustaceans, small fish and insect larvae. Dead fish and even land animals that have fallen in the water are important food sources for these opportunists. Often they are the first on the scene, smelling the food from far away. Unlike most catfish, they are perfectly adapted to swim in open water, even in strong currents.
Pimelodus pictus is found throughout the Amazon and Orinoco River basin, and related species occur as far south as Argentina. Most of the pictus cats on the market are shipped from Colombia and Peru, where they are very common. Because of their keen sense of smell and ability to swim in the current (unusual for catfish), they inhabit the shallow, sandy bottom areas along the major rivers.
In the aquarium, Pimelodus are hardy fish if some basic husbandry rules are followed. The most important is to be careful when handling these fish. The dorsal and ventral fins have exceptionally sharp spines, which can cause two problems. For the aquarist, the sharp barbs can easily pierce the soft skin on your finger, causing painful wounds that often get infected. Although it has not yet been proven, there are indications that this and related catfish may even have weakly venomous properties, as the degree of pain and inflammation suffered when one of their fin spines penetrates the skin seems to be beyond what would be expected from the injury alone. This may be either a reaction to the mucous of the fish getting into the injury, or there may be glandular tissue associated with the spine that generates a toxin.
As for the fish, the skin surrounding the barb and the dorsal and ventral fins is very sensitive. If the fin is torn, an infection is almost always the result. This can lead to a secondary fungus infection that may eventually kill the fish. Often, the fin rays of newly imported specimens are injured while getting entangled in the net during collection. These are best avoided until any infection has been dealt with by the retailer.
The best way to prevent these problems at home is to catch the fish with a net but not lift it out of the water. Use a cup to gently scoop the fish from the net along with the water, and transfer the fish to a bucket. If the net is lifted out of the water, the catfish lock their spines, tangling them in the net – which almost always leads to injuries for the catfish and often for the keeper trying to gently pull the catfish from the net.
It doesn’t help that while the aquarist is trying to disentangle the fins, the fish emits an angry buzzing sound! This is produced by vibrating the pectoral fins in their sockets and resonating the resulting noise using the swimbladder. In nature, this behavior may be used to try to distract predators and in aggressive encounters with members of their own species, but in captivity it only serves to unsettle the already stressed keeper.
As with other scaleless or naked fish, the body of a Pimelodus is covered in very soft, slimy skin. A net or sharp object will scratch this slime coat, causing infections. When they are housed with other catfish such as loricarids and doradids, which have spiny fins and bodies, it is important that enough refuges are available, or serious injury may result from conflicts over the too-few spaces.
Like other scaleless fish, spotted pims are also more sensitive to ich than other species. The parasites can easily attach themselves to the soft skin, so Pimelodus are often the first fish infected if there is an outbreak of this common disease. Fish should always be inspected carefully for ich before being purchased. Fortunately, they can be cured using one of the ich treatments on the market specifically for scaleless fish, although a quarantine aquarium should be considered the ideal way to handle such problems. Unless the disease is quickly dealt with, secondary bacterial infections often result, and once this occurs, treatment will be very difficult.
Pimelodus will eat nearly any fish food offered. Because they are active during the day and at night, they do not require a special feeding schedule like other catfish. They are gregarious eaters that will push other fish out of the way to get the food, and they will even eat from your hand. Flake food, granules, sinking tablets and Tubifex cubes are great dry fish foods. Like all aquarium fish, they cherish frozen foods such as bloodworm and brine shrimp, as well as the occasional live treat, especially small earthworms. Be careful not to overfeed these fish, because they will literally eat themselves to death.
Fish with great appetites and sufficient nervous energy to swim continuously require good water quality and strong filtration. A power filter is a must for pictus catfish, as are regular large-volume water changes. Like many riverine fish, they do not fare well in small aquariums with a less-than-ideal cleaning regimen. Despite their small size, they require aquariums of 30 gallons and larger. Should the water have less-than-adequate oxygen, they can breathe atmospheric air directly from the surface, absorbing oxygen within the walls of their intestines – although when this is observed, it should be an indication that something is amiss with the water quality.
Water conditions are less important. Because the species is widespread in nature, it is quite adaptable. Pictus cats will tolerate a pH of 6.3 to 7.8 and temperatures from 72 to 88 degrees Fahrenheit.
Pictus cats are more comfortable living in groups but will show some aggression among their own kind. At times, as with many catfish, refuges of driftwood or rockwork will be used by the fish, particularly after they have been well fed, when they are likely to retreat to a hiding place to allow digestion to progress. They are generally peaceful toward other fish that they do not regard as prey. Even small Pimelodus, however, can easily consume neon tetras and other similar-sized fish. Some larger tetras and danios, and the young of any breeding fish may be consumed by larger specimens.
Their long whiskers and incessant activity can bother tankmates, particularly those that are inactive when the lights are off. With this in mind, Pimelodus should not be kept with nervous or slow-moving fish such as bettas, angelfish and smaller gouramis. Ideal tankmates are many of the fish often referred to as “bad” community fish: tiger barbs, mid-size cichlids, loaches, larger tetras, other catfish, larger gouramis and red-tail sharks.
Sex cannot be determined with these catfish, though adult females seem rounder than their male counterparts. To date, Pimelodus cats have never been known to lay eggs in captivity, but they are likely to be scatter spawners that do not take care of their eggs or young.
Pimelodus pictus is a great aquarium fish that is easy to keep and will quickly become a family favorite. Kids especially like the constant activity and gregarious nature of these catfish. Sometimes, this fish starts the aquarist off on a quest to find out more about the weird and wonderful range of catfish that are available.