Ancistrus ranunculus L-034

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Ancistrus ranunculus L-034, also called the Medusa Pleco, is a small South American loricariid valued for its unusual appearance and discreet behavior. Native to the Rio Xingu in Brazil, it inhabits rocky areas where flowing water creates a habitat rich in shelter. Its dark body, broad head, and well-developed odontodes give it a distinctive silhouette. This species, with moderate and somewhat irregular availability, is best suited to aquarists who can provide warm, well-oxygenated, stable water. Specimens offered under this name are identified as wild collected.

General species description

Ancistrus ranunculus L-034 is an armored catfish in the family Loricariidae, adapted to life close to the substrate. It is a relatively compact but sturdy species that spends much of its time attached to rocks or hidden in cavities. The L-034 commercial name is used in the aquarium hobby for this Xingu form, while the valid scientific name is Ancistrus ranunculus. Activity generally increases at dusk and after the aquarium lights go out. Despite its impressive appearance, it is usually peaceful with similarly sized fish. It may defend a shelter or spawning site against conspecifics, especially in a confined aquarium. Its commercial rarity is intermediate: it is less common than widely distributed captive-bred Ancistrus.

Geographic origin and biotope

This species comes from Brazil, in the basin of the Rio Xingu, a major Amazonian tributary. Its natural habitat is associated with rocky areas, cracks, and submerged boulders exposed to sometimes strong current. The water is generally warm, clear to slightly tinted, well oxygenated, and low in suspended organic matter in rapids. Bottom surfaces provide both grazing areas for biofilm and shelter. In an aquarium, use a stable arrangement of rocks, wood, and tubes, with effective water circulation. Providing many hiding places helps reduce stress and territorial disputes. Since the species is wild collected, patient acclimation and a thorough quarantine are especially advisable.

Precise location and local name

The geographic reference associated with L-034 is the Rio Xingu in Brazil, particularly its middle section around the Altamira region. Exact coordinates vary among collecting sites and should not be generalized to the entire basin. In the trade and among Brazilian aquarists, loricariids of this type are often grouped under the vernacular name cascudo, a common Portuguese term for several armored catfish. The name Medusa Pleco is mainly an English trade name, inspired by the appearance of the head and odontodes. The designation L-034 belongs to the “L-number” system used to identify loricariids exported before scientific determination or alongside it. Keeping both the code and scientific name in breeding records is advisable.

Appearance and physical characteristics

The body of Ancistrus ranunculus L-034 is stout, ventrally flattened, and covered with bony plates. Its base color ranges from grayish brown to very dark brown, often appearing uniform or subtly mottled depending on lighting and condition. The head is broad, with an inferior sucker mouth used to cling to rocks. Adult males develop more visible odontodes on the head and pectoral fins, contributing to the name Medusa Pleco. The pectoral fins are strong and help the fish hold position in current. The eyes may appear relatively small compared with the width of the head. Adult size remains modest for a loricariid, but the species still needs a structured, well-filtered aquarium to support its bottom-dwelling behavior and need for shelter.

General diet

Ancistrus ranunculus L-034 is primarily a grazer, feeding on biofilm, soft algae, and microorganisms found on surfaces. In captivity, regularly provide sinking wafers or tablets containing plant matter, along with blanched vegetables such as zucchini or cucumber. Complete algae-based foods can supplement the diet. A small amount of richer, protein-based food may be offered occasionally, especially during growth or breeding, but it should not dominate the menu. Natural wood provides a useful grazing surface and a structural element in the aquarium. Feedings are best offered after the lights go out, when the fish becomes more active. Remove leftovers to protect water quality and make sure faster tankmates do not monopolize the food.

Essential data

• Native river: Rio Xingu
• Local name used: Cascudo
• Origin of the scientific name: Ancistrus is the genus name; ranunculus is the specific epithet.
• Meaning of the full name: Ancistrus comes from the Greek ankistron, meaning hook; ranunculus means little frog in Latin, referring to the animal’s general appearance.
• Common and vernacular names: Medusa Pleco, L-034, cascudo
• Family: Loricariidae
• Subfamily: Ancistrinae
• Name pronunciation: an-SIS-trus ra-NUNK-yoo-lus
• Discovery: Hans-Georg Müller and Claude Weber, 1992
• Maximum adult size: Approximately 15 cm
• Water temperature and pH: 26 to 30 °C; pH 6.0 to 7.5
• Watercourse appearance and surrounding vegetation: Rocky areas with warm, well-oxygenated water; aquatic vegetation is often less abundant in fast-flowing zones.
• Typical tankmates: Hypancistrus zebra L-046, Krobia xinguensis, Baryancistrus xanthellus L-018, Aphanotorulus ammophilus L-123
• Temperament and behavior: Peaceful, secretive, bottom dwelling, and mainly active at dusk; may defend shelters.
• Water depth: Shallow to intermediate areas associated with rocky substrates.
• Sexual dimorphism: Males have more developed odontodes on the head and pectoral fins; females have a broader abdomen.
• Bottom structure and flow: Rocky blocks and slabs, cracks, and moderate to strong current depending on the area.

In your aquarium

Success with Ancistrus ranunculus L-034 depends on warm, clean, highly oxygenated water and a layout offering several shelters. A mature aquarium, effective filtration, and well-distributed current are preferable to stagnant conditions. Feed it after lights-out with a varied plant-based diet, then monitor body condition, especially after receiving a wild specimen. Avoid excessive bottom competition and aggressive tankmates. With careful acclimation and stable parameters, this Medusa Pleco can become a discreet, long-lived, fascinating resident.