Let me start by saying there is no such thing as the “Common” pleco. The word common is used as a coverall to describe many different types of the species.  Nearly all the fish covered by this catch all are mis-sold to hobby aquarium keepers who through lack of knowledge and awareness end up causing harm to the fish.

In my view fish retailers should make the prospective buyers more aware of the potential size the fish will grow to and refuse to sell even babies to anyone with a tank smaller than about 150 litres.  These can grow to be BIG fish.

Introduction to Plecos

Pleco is a name used for the catfishes of the family Loricariidae . One of the species in this family is named Hypostomus plecostomus and the name Pleco is derived from the name of this species. Today, the name Pleco is used not only for Hypostomus plecostomus but for all the members of the family Loricariidae . Plecos are also known as armored catfishes, since the longitudinal rows of scutes present on the upper part of the fish resembles old-fashion armor.

If you purchase a Common Pleco in a fish store it can be one of several species, including Suckermouth Catfish ( Hypostomus plecostomus ), Bristlenose Catfish ( Ancistrus dolichopterus ), Sailfin Catfish ( Liposarcus multiradiatus ) or Amazon sailfin catfish     ( Liposarcus pardalis ). The name Common Pleco is used for a lot of different brown-mottled Plecos that grow rather big in the aquarium. They all have similar habits and requirements, so this article is of interest even if you do not know exactly which species of pleco you keep.

The maximal lifespan of common plecos is not known, but it is believed to be around 20-30 years in captivity.

Pleco size

The fish sold under the name Common Pleco in fish stores is normally no bigger than 5-10 cm (2-4 inches) but this doesn’t mean that it will stay like that forever. Unfortunately, a lot of aquarists purchase fish without first finding out how big they can get as adults. In the case of the common pleco, you should expect your fish to eventually reach a size of 30-60 cm (1-2 feet).

Pleco habits

The common plecos are nocturnal creatures that are quite passive during the day. As long as the aquarium is lit, the pleco will use its specialized omega iris to keep the light from entering its eyes. When the lights are turned off in the evening, the omega iris will open and the fish will start searching for food.

Pleco temperament and suitable tank mates

Unlike many other plecos, the species normally sold under the name Common pleco are territorial and keeping two or more large Common plecos together is rarely it good idea. It might work out fine, but you are definitely taking a risk and you should be prepared to evacuate promptly if they fail to tolerate each other. Different individuals have different temperaments and the temperament can also change gradually as the fish ages. The risk for violence is probably lower if you combine large common plecos from different species with each other, but more research is necessary before we can say anything for sure. An interesting exception is the Bristlenose catfish ( Ancistrus dolichopterus ), a lot of aquarists have managed to keep more than one Bristlenose catfish in the same aquarium (regardless of fish size).

A lot of different fish species can be housed together with Common pleco, but fat or flat bodied fish – such as goldfish and discus – should be avoided since plecos are found of sucking on such fishes.

Aquarium for common pleco

Aquarium size

Since the species sold under the name common pleco can become so big, the fishes will eventually need big aquariums. If you purchase common pleco for your small aquarium you must therefore be prepared to eventually get a bigger aquarium or find a new home for your common pleco. Large adult specimens normally need at least 200 – 375 litres (roughly 50 – 100 gallons) since they can reach a length of 30-60 cm (roughly 1-2 feet).

Use a lid!

It is important to cover the aquarium when keeping common pleco because they are capable jumpers. In the wild, plecos can use this ability to escape to better conditions during dry periods. They can not really travel on land, but they are strong enough to wiggle their way from a shallow puddle to deeper puddle in a drying riverbed. To a certain extent, they are capable of absorbing oxygen directly from the air so they will last longer on land than many other fish. If you come home and find your pleco seemingly unconscious on the floor, you should put it back in the aquarium because it might not be dead yet.

Do not let the water go all the way up to the lid, because the common pleco wants to be able to swim up to the surface and gulp air. The fish uses the air to control its buoyancy.

Aquarium decoration

When you set up an aquarium for the common pleco it is important to keep in mind that this fish eats plants. If you wish to use live plants, pick really sturdy and fast growing species and keep your fingers crossed. You can for instance try java moss, java fern och some sturdy crinum species. Also keep in mind that plecos are fond of uprooting plants. Use heavy stones to secure the area around each plant or go for floating plants and plants that can be anchored to aquarium decoration instead of planted in the substrate. Last but not least, keep your common pleco well fed at all times. A pleco that is given plenty of yummy vegetables in the aquarium is less likely to devour the plants.

Keeping common pleco in a barren aquarium is not a good idea since this fish likes to have a safe place where it can stay hidden and rest during the day. Live plants are however by no means mandatory in a pleco aquarium since there are many other forms of decorations that can be used to construct borders, create hiding spaces and make the fish feel at home. You can for instance use flower pots, stones, caves and artificial plants. You should also ALWAYS include driftwood in the aquarium setup since the common pleco needs to chew on wood to stay happy and healthy.

Water conditions in the aquarium

The common pleco hails from fast moving waters and will therefore appreciate powerful water currents and high oxygen levels in the aquarium. The water temperature should be kept in the 20-28 degrees C (68-82 degrees F) range and rapid changes in water temperature should be avoided. Healthy common plecos are however quite resilient and can survive in both cooler and warmer conditions, at least for a while. The common pleco needs soft water and the pH-value should be kept in the 6.0-7.5 range (acidic to slightly alkaline).

The common pleco produces quite a lot of waste. Regularly vacuum up the faeces and change 30-50% of the water each week. If you allow the water quality in the aquarium to drop, it can make the pleco think that the dry season has started and that its home is about to dry out. In order to save itself, it might try to escape by jumping out of the aquarium. A desperate pleco can bash itself against the aquarium lid until it sustains severe injury or even dies.

Food for common pleco

The common pleco is famous for its ability to keep the aquarium algae free, but you should always supplement the natural algae growth with additional food to make sure that your common pleco receives all necessary nutrients. The pleco is an omnivorous species, but meaty food should only make up a small part of its diet. For small plecos, uneaten scraps of the meaty food you serve other omnivores in the aquarium will often be enough. Large plecos can be given shrimps and fish fillets once in a while.

Since the common pleco feed on algae and plant matter in the wild, it will appreciate algae and plant based food in the aquarium. You can for instance use spirulina tablets or wafers as a base. Spirulina flakes float and might therefore be gulped down by faster fish in the aquarium before the pleco gets at chance to find them. Some plecos will however learn to quickly swim up to the surface during feeding time.

In addition to dry prepared foods, give your common pleco some fresh fruits and vegetables. You can for instance serve cucumber, zucchini, squash and similar vegetables. Lettuce and other leafy vegetables are also highly appreciated. There is no need to boil of blanch fruits and vegetables. A practical way of feeding common pleco is to get a vegetable holder for the aquarium or make one using a clothes-pin or similar.

Last but not least, an aquarium where you keep common pleco should always include driftwood since the fish needs wood to chew on. Wood is an importance source of fibre for common plecos.

Breeding common pleco

Sexing common pleco

Sexing the common pleco is really tricky, but in some species the males tend to be smaller than the females and develop bigger barbells. Some sources claim that the chin barbells are somewhat smoother in females. The Bristlenose Catfish is fairly easy to sex since the females do not develop any “horns”.

Breeding common pleco

Breeding common pleco in captivity is hard and only a small number of aquarists have managed to successfully raise common pleco fry in their aquariums. As mentioned above, large adults can be highly territorial so at big aquarium (750 litres / 200 gallons or more) with plenty of suitable hiding spots is recommended if you want to try breeding common pleco. In the wild, the common pleco prefers to use caves along the river bank as spawning sites and such conditions are naturally quite hard to mimic in the aquarium. When common plecos are bred in captivity for the aquarium hobby, they are normally bred in ponds, not in aquariums.

One of the easier plecos to breed in captivity is the Bristlenose catfish ( Ancistrus dolichopterus ). This species does not need a cave along a river bed; it will happily breed in a normal stone cave or flowerpot in the aquarium. Make sure that you plecos are happy and healthy in the aquarium and keep them on a nutritious and varied diet. It is also important that you provide them with optimal conditions when it comes to water quality, water chemistry, and so on. If you are lucky, your couple will get into spawning mood and the male will attract the female to the cave. The female will deposit the eggs and the male will stay around after fertilization to care for the offspring. He will also chase away predators. After 4-8 days the eggs will hatch and the fry will be free swimming within another 4-6 days.