L333 King Tiger Pleco (Hypancistrus seideli)

A classic Rio Xingu L-number pleco with bold black-and-cream maze patterning, compact Hypancistrus proportions, and excellent potential as a collector or breeding fish.

The L333 King Tiger Pleco is one of the best-known ornamental Hypancistrus from Brazil's Rio Xingu. For decades it was traded simply as Hypancistrus sp. L333, but modern taxonomic work has now formally placed L333 within the species Hypancistrus seideli.

L333 is famous for its irregular black vermiculations over a pale cream, yellowish, or off-white background. The pattern can form stripes, loops, maze-like markings, and broken bands across the head, body, and fins.

No two King Tigers look exactly alike. Pattern width, colour contrast, body shape, and markings can vary significantly between individuals, making strong L333 lines especially appealing to Hypancistrus collectors and breeders.

Why this pleco stands out

• Classic L333 King Tiger aquarium phenotype
• Bold black-and-cream worm-line and maze pattern
• Officially classified as Hypancistrus seideli since 2025
• Compact adult size compared with many larger plecos
• Excellent cave-spawning breeding species
• Peaceful with suitable community fish
• Strong collector value among L-number pleco enthusiasts

Best for

• L-number pleco collectors
• Hypancistrus enthusiasts
• Dedicated pleco breeding projects
• Warm, highly oxygenated South American aquariums
• Peaceful community tanks with suitable bottom space
• Aquarists looking for L333 King Tiger Plecos in Canada

Topick Aquarium Insight

L333 is a good example of why the L-number still matters even after a fish receives a formal scientific name.

Modern taxonomy places L333 together with several other Rio Xingu forms within Hypancistrus seideli, but an L333 breeding line still has a recognizable visual goal in the aquarium hobby. Customers buying L333 usually want the classic broader, irregular King Tiger maze pattern rather than simply any fish scientifically identified as H. seideli.

For that reason, we recommend maintaining established L333 lines separately from other H. seideli morphs if preserving the traditional L333 appearance is the goal.

We also do not recommend treating King Tigers as algae-cleaning plecos. Their feeding requirements are different from a typical Bristlenose and should include a varied omnivorous diet with a meaningful protein component.

Is L333 Now Hypancistrus seideli?

Yes. L333 was historically known as Hypancistrus sp. L333 because the fish had not yet received a formal scientific species name.

In 2025, a major study of Rio Xingu Hypancistrus formally described Hypancistrus seideli. The species includes aquarium forms traditionally identified as L066, L236, L287, L333, L399, and L400.

The L-numbers remain extremely useful in the aquarium hobby because these forms can look dramatically different despite belonging to the same scientifically recognized species.

L333 vs L066 King Tiger Pleco

L333 and L066 were historically sold as separate L-number forms, but genetic and taxonomic research has shown that both belong to the same species, Hypancistrus seideli.

• L333: traditionally associated with a stockier body and broader, more irregular King Tiger markings
• L066: traditionally associated with a more slender body and finer worm-like lines, often with a more deeply forked tail

Intermediate appearances exist, which is one of the reasons scientific work ultimately treated them as colour and body-form variation within the same species.

L333 vs L236 Pleco

L333 and L236 are also now included within Hypancistrus seideli, but their traditional aquarium phenotypes are different.

• L333: usually selected for broader black-and-cream King Tiger maze or worm-line patterning
• L236: traditionally associated with much higher black-and-white contrast and a more fragmented, cracked or highly broken pattern

Because modern selectively bred lines can become extremely variable, L-number identification should ideally be based on known lineage rather than appearance alone.

Appearance & Pattern Variation

L333 King Tigers show alternating pale and dark vermiculations across the head, body, and fins. The markings can be narrow, broad, connected, broken, or strongly maze-like depending on the individual.

Juveniles often show especially strong contrast. Pattern proportions and overall appearance can change significantly as the fish grows.

Natural variation may include:

• Black line thickness
• Cream to yellowish background colour
• Number and shape of maze-like markings
• Fin banding
• Tail pattern
• Body depth
• Contrast changing with maturity

Unless specifically listed as WYSIWYG, product photos should therefore be considered representative of the offered L333 line rather than an exact image of every fish sold.

Origin & Natural Habitat

Hypancistrus seideli is native to the Rio Xingu system in Pará, Brazil. It occurs across the lower Xingu and downstream portions of the Volta Grande region.

The species has been documented in an unusually broad range of habitats for Hypancistrus, including rocky areas with strong current as well as deeper and slower-flowing sections of the lower Xingu.

Rocks, crevices, high dissolved oxygen, and warm clean water are important features to reproduce in an aquarium.

Behavior & Temperament

L333 King Tiger Plecos are generally peaceful toward midwater community fish.

Like most Hypancistrus, however, adults can become territorial toward other bottom-dwelling plecos, especially around preferred caves. Mature males may defend breeding caves particularly strongly.

Multiple L333 can be maintained together when sufficient floor space, caves, visual barriers, and feeding opportunities are provided.

Tank Setup

L333 originates from the warm Rio Xingu system and benefits from excellent oxygenation despite the relatively high temperature required.

• 30 gallons or larger recommended for an adult pair
• 40–55 gallons or larger preferred for a group
• Long footprint preferred over a tall narrow aquarium
• Provide multiple caves and rock crevices
• At least one suitable cave per adult male
• Strong biological filtration
• High dissolved oxygen
• Moderate to strong water movement
• Driftwood and smooth rocks provide cover and structure
• Mature, stable aquarium strongly recommended

Warm water holds less dissolved oxygen than cooler water. This makes strong surface movement, adequate filtration, and good oxygenation particularly important for Rio Xingu Hypancistrus.

Water Parameters

• Current Scientific Name: Hypancistrus seideli
• L-Number: L333
• Former Designation: Hypancistrus sp. L333
• Common Names: King Tiger Pleco, L333 King Tiger Pleco, Golden King Tiger Pleco
• Origin: Rio Xingu, Pará, Brazil
• Adult Size: approximately 12–15 cm
• Temperature: approximately 26–30°C
• pH: approximately 5.5–7.5
• Hardness: soft to moderately hard water
• Temperament: Peaceful toward most fish; territorial around caves
• Diet: Omnivore with protein-rich foods important
• Care Level: Intermediate

Stable temperature, excellent oxygenation, clean water, and low organic waste are more important than constantly adjusting the aquarium to hit one exact pH value.

Feeding

L333 King Tiger Plecos are omnivorous Hypancistrus and should not be fed like a primarily herbivorous Bristlenose Pleco.

A varied diet can include:

• High-quality sinking pleco pellets
• Protein-rich sinking foods
• Frozen bloodworms in moderation
• Frozen brine shrimp
• Krill-based foods
• Mussel or similar aquatic invertebrate-based foods in moderation
• Quality omnivore wafers
• Some algae and vegetable-containing foods
• Natural biofilm and aufwuchs

Do not rely on aquarium algae as the main diet. L333 is not an algae-control replacement for a Bristlenose Pleco.

Feeding after the lights dim can help shy individuals receive enough food in busy community aquariums.

Is L333 a Good Algae Eater?

L333 will graze biofilm and naturally occurring material from rocks and wood, but it should not be purchased primarily for algae removal.

Compared with a typical Bristlenose Ancistrus, the King Tiger Pleco requires a more omnivorous and protein-inclusive diet. Dedicated sinking foods should always be provided.

Tank Mates

L333 can live successfully with a wide variety of peaceful tropical fish that tolerate warm water.

• Warm-water tetras
• Suitable rasboras
• Discus in appropriately maintained aquariums
• Peaceful dwarf cichlids
• Suitable Cory-type catfish that tolerate the temperature
• Other peaceful medium-sized community fish

Temperature compatibility is especially important. Fish that prefer cool water should not be maintained permanently at Xingu Hypancistrus temperatures simply to share the same aquarium.

Multiple bottom-dwelling plecos require enough caves and territory to prevent chronic competition.

Shrimp & Snail Compatibility

Adult shrimp may coexist with L333 in sufficiently large, structured aquariums, but the species is an omnivore and should not be considered completely shrimp-safe.

Small shrimplets and vulnerable invertebrates may be eaten opportunistically. A dedicated shrimp aquarium is more appropriate when maximum shrimp reproduction is the goal.

Peaceful snails are generally less of a concern, although newly hatched or very small invertebrates cannot be guaranteed safe.

Male vs Female L333

Sex becomes easier to determine once L333 reaches maturity.

• Males: generally develop a broader head and stronger odontodes around the cheeks, pectoral-fin spines, and rear portion of the body
• Females: generally show less-developed odontodes and become broader through the abdomen when carrying eggs

Juveniles should not be sold with guaranteed sex unless external differences are already clearly developed.

Breeding

L333 King Tiger Plecos are cave spawners and can reproduce reliably in aquariums once mature and properly conditioned.

A male selects a narrow cave and typically guards it. During spawning, the female enters the cave and deposits an adhesive egg cluster. After fertilization, the male remains with the eggs, fanning and protecting them until they hatch.

Good oxygenation around breeding caves is particularly important. Once fry consume their yolk sacs, they can be offered appropriately sized high-quality sinking foods, baby brine shrimp, and other nutritious foods.

Breeders wishing to maintain a recognizable L333 line should avoid mixing breeding colonies with L066, L236, or other Hypancistrus seideli phenotypes. Although these are now classified within the same species, crossing lines can make the traditional L-number appearance increasingly difficult to preserve.

Why L-Numbers Still Matter

L-numbers were originally used to identify loricariid forms before their scientific identity was fully resolved. In many cases, including L333, the aquarium name became established long before modern taxonomic research caught up.

Although L333, L066, L236, L287, L399, and L400 are now included within Hypancistrus seideli, these numbers remain useful for describing recognizable aquarium phenotypes, historic collection forms, and breeding lines.

For serious collectors, both pieces of information matter: the scientific species tells us what the fish is biologically, while the L-number tells us which aquarium form we are trying to preserve.

Canada-Wide Live Fish Shipping

L333 King Tiger Pleco is available from Topick Aquarium in Canada when in stock. Local pickup is available in Markham, Ontario, and Canada-wide live fish shipping may be available depending on weather, route, size, and livestock condition.

Important Note

L333 was historically listed as Hypancistrus sp. L333. Since the formal 2025 description, the currently accepted scientific name is Hypancistrus seideli.

L333 represents one recognizable aquarium phenotype within a highly variable species. Individual line width, background colour, body shape, contrast, and pattern naturally vary and can also change as the fish matures.

Unless specifically listed as WYSIWYG, product photos should be considered representative of the offered L333 line rather than an exact image of every fish sold.

FAQ

What is an L333 King Tiger Pleco?
L333 is a Rio Xingu Hypancistrus traditionally known as the King Tiger Pleco. Since 2025, it has been scientifically classified within the species Hypancistrus seideli.

What is the scientific name of L333?
The currently accepted scientific name is Hypancistrus seideli. Older aquarium references commonly list the fish as Hypancistrus sp. L333.

Is L333 the same species as L066?
Yes. Genetic work and the formal 2025 species description place both L333 and L066 within Hypancistrus seideli. They remain useful aquarium designations for different traditional phenotypes.

Is L333 the same as L236?
They are now classified within the same species, Hypancistrus seideli, but the aquarium hobby traditionally maintains them as different visual forms and breeding lines.

Why does L333 still have an L-number if it has a scientific name?
The L333 designation remains useful because it identifies the traditional King Tiger phenotype and breeding line within the highly variable species Hypancistrus seideli.

How big does an L333 King Tiger Pleco get?
Adults commonly reach approximately 12–15 cm depending on the individual and whether total or standard length is being measured.

What temperature does L333 need?
Approximately 26–30°C is appropriate. Because this is warm water, strong oxygenation and good water movement are particularly important.

Is L333 a good algae eater?
It grazes biofilm and naturally occurring material, but it is not an algae-control pleco. L333 is omnivorous and requires a varied diet including quality protein-rich sinking foods.

Does L333 need driftwood?
Wood is useful for cover, structure, and biofilm growth, but unlike some wood-eating loricariids, L333 does not depend on eating wood as a primary dietary requirement.

Does L333 need a cave?
Yes, caves are strongly recommended for security and become essential if breeding is the goal. Mature males select and defend suitable spawning caves.

Can L333 King Tiger Plecos live together?
Yes, provided the aquarium offers sufficient floor space, caves, visual barriers, and feeding opportunities. Mature males may become territorial around preferred caves.

Can L333 breed in an aquarium?
Yes. L333 is a cave-spawning Hypancistrus and has been bred successfully in captivity for many years. The male guards and fans the eggs inside the breeding cave.

Will every L333 have the same pattern?
No. Pattern variation is one of the defining characteristics of this fish. Line thickness, maze structure, cream colour, black coverage, fin markings, and body shape can all differ between individuals and change with age.

Can I breed L333 with L066 or L236?
They are now classified within the same species and can reproduce together, but we do not recommend mixing them in a breeding project if preserving a recognizable L333 line is the goal.