Pleco Fish L-number history and the best L-Pleco for your Tank

The scientific naming system for species is comprised of two parts: Genus and Species, for example, the Sailfin Plecostomus has the scientific name: Pterygoplichthys gibbiceps. The name meaning “lump head” however, this species also goes by the L-number: L083. Scientific names are often translated to simple describing words of the features the animal exhibits. This naming system was developed and has been used since the 1700’s.

When fish keeping started to become increasingly popular around the 20th Century, fish were imported in the masses for the aquarium trade, including many species of Plecostomus or “plecos.” These fish were literally being imported faster than they could be officially named and classified; this led to many names originating for the same species. As you can imagine this quickly became fairly confusing.

The first official “L-number” was published in 1988, by the German Aquarium Magazine DATZ (the Aquarium and Terrarium Magazine). The “L” in the name comes from “Loricariidae” which is the very large catfish family these Plecos belong to. This categorising of the Pleco fish into L-numbers is not a formal scientific designation, but allowed people at the time to identify a common name for each species. Some L-numbers have been used for multiple species, so it is always best to check the scientific name if they now have one, or the common name of the species you are purchasing.

Would an L-pleco be suitable for me?

There are 600 Documented L-numbers currently, so picking the right one for your tank can be tricky. It is best to think in terms of how big your set up is going to be or how big it already is, most species of Pleco reach around 20cm size with the largest common Pleco reaching a whopping 24” in size.

The large majority of Plecostomus fish are native to South America; these are often found in fast-flowing streams with a rocky substrate. Bear in mind that each species is unique so it is always best to research so you can create the most suitable habitat and conditions to keep your Pleco happy. They are generally quite hardy fish, preferring a temperature of 24-32 degrees and a PH between 6.5-8. Most Plecos will be happy in a 200-litre tank, with some species such as the Royal Plecostomus (Panaque nigrolineatus) needing at least 600 litres.

These species are very often sold as Algae eaters; however, this is often not the case, with most Pleco fish species being opportunistic feeders eating both meat and organic matter. Their diet can include most frozen foods and pleco pellets, it is always best to check which diet your pleco prefers. The general life-span of a Pleco is 10 to 15 years, so they are a long term investment.

Some popular L-plecos and their care

The Zebra Pleco L-046 (Hypancistrus zebra)

Aquarium Requirement

The Zebra pleco has quite demanding needs and so is one of the more difficult plecos to keep. They require quite warm oxygenated water with a neutral PH. It is important that all water parameters are kept stable. They require a high tank temperature so ensure when you are doing water changes that the new water is warm so as not to shock them. The substrate should be sand, gravel or rocks. The tank should also include many hiding spots to reduce stress.

• Tank size: 100+ Litres
• Temperature: 28-31 Degrees
• PH: 6-7


The Zebra pleco is an omnivore and requires high protein foods. Vegetables such as peas, lettuce leaves, cucumber should also be provided. Plec pellets and frozen meaty foods should also be provided.


The most compatible fish are Discus (Symphysodon sp.) as they have similar requirements. They are non-aggressive so can be kept with peaceful community fish, but bear in mind their tank requirements are not suitable for most community fish. They can be kept together in a group, preferably with one male and multiple females.

The Cactus Pleco L-114 (Pseudacanthicus cf. leopardus)

Aquarium Requirement

The Cactus Pleco will grow to around 12” in size, so they require a larger aquarium. They will require well-oxygenated water, plenty of driftwood and root-like structures and large, hardy plants. These large plecos can produce lots of waste so a good filtration system is important.

• Tank size: 300+ litres
• Temperature: 23-27 degrees
• PH: 6.5-7.5


Cactus Plecos are omnivores so they should be fed a good mix of veg and meat, pleco pellets will also be accepted. Some suitable foods include chopped shrimp, Krill, Mysis and veg such as Lettuce and Cucumber.


They are compatible with most community fish and as they are large in size they can also be kept with some of the more aggressive cichlid species.

The Snowball Pleco L-201 (Hypancistrus sp.)

Aquarium Requirement

This is smaller pleco reaching 5-6” so a medium-sized aquarium is suitable. They require a high water flow with plenty of oxygen. Lots of bogwood, driftwood, rocks and other hiding places are required.

• Tank size: 150+ litres
• PH: 5.5-7.5
• Temperature: 22-29 degrees


The Snowball Pleco is omnivorous so will require a mixed diet of veg, frozen foods and Pleco pellets.


The snowball Pleco is a very peaceful community fish, males may become territorial with other males of their species.

The King Tiger Pleco L-333 (Hypancistrus sp.)

Aquarium Requirement

The King Tiger Pleco is another of the smaller plecos, reaching around 5” in size. They will require a set-up of rocks, driftwood, bogwood, roots and plants. They require a high water flow with plenty of oxygen.

• Tank Size: 120+ Litres
• Temperature: 25-29 degrees
• PH: 5.5-7.5


These are mainly carnivorous species; they should be fed plenty of carnivore Pleco pellets as well as frozen foods such as shrimp, bloodworm, muscles and krill. Vegetable items should also be offered and are often accepted.


These are a very peaceful species that can be kept in general community tank. They can become territorial towards other males of the same species and should not be kept with dwarf shrimp they may predate.