Royal pleco - Panaque nigrolineatus

Scientific name: Panaque nigrolineatus

Common name: Royal pleco

Family: Loricariidae

Usual size in fish tanks: 38 - 43 cm (14.96 - 16.93 inch)

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Recommended pH range: 6.7 - 7.5

Recommended water hardness: 4 - 15°N (71.43 - 267.86ppm)

0°C 32°F30°C 86°F

Recommended temperature range: 22 - 27 °C (71.6 - 80.6°F)

The way how these fish reproduce: Spawning

Where the species comes from: South America

Temperament to its own species: peaceful

Temperament toward other fish species: peaceful

Usual place in the tank: Bottom levels

General Information

The Royal pleco (Panaque nigrolineatus) is a large loricariid from the Orinoco and parts of the Amazon basin (Brazil, Colombia, Venezuela). It’s famous as one of the few fishes that truly ingest and digest wood (xylivory) with help from gut microbes. Verified maximum size is about 43 cm SL (≈16.9″; larger in TL). Plan for an adult big fish footprint and heavy filtration.

Food & Feeding

Driftwood is non-negotiable. Provide multiple chunks/branches for constant rasping; this species relies on wood fiber and aufwuchs as a major dietary component. Supplement with plant-rich sinking wafers/pellets, spirulina, and blanched veg (zucchini, cucumber, peas). Offer protein (mysis, shrimp, bloodworms) sparingly. Expect copious “sawdust” waste—tune filtration accordingly. The wood diet and microbiome are well-documented in studies of P. nigrolineatus.

Sexing

Reliable external dimorphism is limited. As in many ancistrine plecos, experienced keepers may use genital papilla shape on mature fish (female blunt/rounded vs. male smaller/pointed), but this is not foolproof. Overall head width/odontode development can vary and is not a consistent field mark for this species.

Breeding

No verified natural home-aquarium spawnings are documented for P. nigrolineatus. Hobby reports discuss experimental hormone induction, but routine captive breeding for the hobby is essentially unreported. Assume your specimen is wild-collected unless stated otherwise.

Lifespan

Commonly cited at 10–12 years with excellent care—large systems, high oxygen, clean water, and constant access to wood.

Tank Requirements & Water Parameters

Volume & footprint: plan for ~500 L / 130 gal with a long footprint for a single adult; more for communities. Big bio-load from wood rasping demands oversized filtration and strong aeration/flow.
Water: pH ~6.7–7.5, hardness ~4–15 °dH, temperature 22–27 °C (71.6–80.6 °F). Keep nitrate very low and oxygen high (riverine origin).
Décor: deep sand/fine gravel plus substantial driftwood (primary feature); add rock for shade and lanes to cruise. Expect them to chew through branches over time.
Maintenance: large, frequent water changes; prefiltering and mechanical stages to handle wood particulates.

Compatibility & Tank Mates

Generally peaceful toward dissimilar species; avoid bite-size fish that might be outcompeted at feeding. Can be territorial with conspecifics or similar wood-grazing plecos—provide multiple wood piles/caves and ample space if attempting groups. Works with robust characins, peaceful cichlids, and larger catfish in very spacious tanks.

Behaviour & Usual Place in the Tank

Bottom levels (nocturnal bentho-rover): hides by day under/inside wood; emerges to rasp wood and graze surfaces—often more diurnal once settled. Provide shaded retreats and open patrol lanes between wood stacks.

Identification Notes

The trade groups several “Royal” forms (L-numbers such as L190/L191/L027/L330). True P. nigrolineatus shows bold dark stripes/squiggles on a grey body; closely related forms and the subspecies P. n. laurafabianae (“watermelon pleco”) differ in spotting vs. striping and locality. Expect variation by collection area.

Short Description

Royal pleco (Panaque nigrolineatus) is a true wood-eating loricariid from the Orinoco and parts of the Amazon. Keep in a very large, high-oxygen, driftwood-rich aquarium with strong filtration; feed plant-heavy sinking foods and vegetables alongside constant wood access. Captive breeding in hobby tanks remains unproven.

Q&A

Where exactly is it from? Orinoco and some Amazon tributaries across Brazil, Colombia, Venezuela.
How big does it get? Up to about 43 cm SL in scientific records; adults are bulky and need a very large tank.
Do they “need” wood? Yes—this species ingests/rasps wood and harbors gut microbes linked to cellulose breakdown; always provide driftwood.
Breedable at home? No reliable home spawnings are documented; occasional discussions of induced methods exist but are not routine.