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Hoppe's otocinclus

Otocinclus hoppei

A small loricariid catfish from Brazil (Tocantins, Madeira and Paraguay basins): streamlined body of just 3 cm with a sucker mouth for clinging to surfaces and scraping algae and biofilm. Like cousin O. cocama, it is a tireless, peaceful algae grazer that represents the perfect cleaning crew for planted aquariums. Must be kept in groups of at least 6 in mature tanks with established algae. Often arrives malnourished: supplement with zucchini and wafers. Copper and water quality sensitive.

Taxonomy

Class:Actinopteri

Order:Siluriformes

Family:Loricariidae

Subfamily:Hypoptopomatinae

Genus:Otocinclus

Species:Otocinclus hoppei

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Water Temperature

21 - 26 °C

pH Value

6 - 7.5

Water type

Freshwater

Tank level

Bottom and middle

Adult size

4 cm

Minimum tank volume

>= 40 L

Minimum group

>= 6

2 - 15 dGH

0 - 12 dKH

TDS

30 - 345 ppm

Conductivity

47 - 539 uS/cm

Species description

Geographical Origin and Habitat: Endemic exclusively to the vast, incredibly complex lower Amazon River basin, specifically heavily concentrated around the pristine, fast-flowing, and highly oxygenated clearwater tributaries near Belém and the Tocantins River in Brazil, South America. Otocinclus hoppei (universally known as Hoppe's Oto or the Dwarf Suckermouth Catfish) natively colonizes the shallow, sun-drenched margins of these rivers. These specific micro-habitats are completely choked with massive, dense forests of submerged aquatic vegetation, thick layers of periphyton (algae), and massive tangles of submerged roots.

Taxonomy and Morphology: Scientifically classified within the Loricariidae family (the armored suckermouth catfishes), it is a spectacular, deeply specialized, and unbelievably tiny micro-scavenger. Morphologically, fully mature adults rarely exceed 3.5 to 4.5 centimeters (1.4-1.8 inches) in length, making them one of the smallest Loricariids in the world. It possesses a deeply robust, heavily armored, bullet-shaped body profile. Its absolute defining anatomical feature is its specialized, downward-facing "suckermouth" perfectly evolved for stripping microscopic diatoms and soft green algae from broad leaves and smooth river stones.

Social Behavior: They are exceptionally peaceful, deeply timid, and absolutely obligate shoaling micro-catfish. Unlike large Plecos which are solitary and territorial, Otocinclus are highly gregarious. They strictly MUST be kept in a sizable group (absolute minimum 6, but 10-20+ is vastly superior to observe their natural confidence). In the aquarium, they possess a hyper-active, nervous energy, spending their entire day frantically darting from leaf to leaf, completely plastered against the glass or broad plants, relentlessly scrubbing surfaces for microscopic food.

Coloration and Sexual Dimorphism: Sexual dimorphism is subtle and impossible to determine from above; mature females are noticeably broader and plumper when viewed from below, while males remain distinctly slimmer. The coloration of Hoppe's Oto is a brilliant evolutionary camouflage (mimicking a shadow on a leaf): the base body is a pale, silvery-grey, faint olive, or yellowish-brown. Its absolute defining feature is a massive, incredibly stark, pitch-black horizontal stripe running straight from the snout, through the eye, terminating at the base of the tail.

Care, breeding and tankmates

Aquarium Setup: The aquarium architecture MUST flawlessly replicate a sunlit, heavily planted, and highly oxygenated Amazonian clearwater tributary. A minimum 60-liter (15-gallon) tank is required for a small school. The absolute most critical requirement is overwhelming, dense vegetation and established surfaces. The tank MUST be densely packed with broad-leaved plants (like Anubias or Amazon Swords) to provide massive grazing surfaces. The tank MUST be fully mature and seasoned for at least 3-4 months before introducing Otocinclus to ensure a massive, established microscopic biofilm exists.

Diet and Feeding: They are highly specialized, absolutely obligate algivores (algae-eaters) and biofilm grazers. This is the single most critical aspect of their care. They physically require a constant, massive supply of soft green algae and microscopic diatoms to survive. Because they are wildly efficient, they will completely strip a pristine tank of algae in days and rapidly starve to death. You MUST heavily supplement their diet daily with blanched vegetables (zucchini, cucumber, spinach) and high-quality sinking algae wafers.

Water Quality: Originating from pristine, fast-flowing Amazonian clearwater, they strictly demand highly stable, immaculate, intensely oxygenated, and soft water. They thrive in warm tropical temperatures (23-28°C / 73-82°F). Crucially, they require soft to moderately hard water (GH 2-10) and a slightly acidic to neutral pH (6.0 - 7.5). They possess absolute zero tolerance for dissolved organic waste, Ammonia, or Nitrites; rigorous weekly water changes are absolutely mandatory. The water flow MUST be moderate to strong to ensure maximum oxygen saturation.

Compatibility and Cohabitation: Compatibility is excellent, provided tankmates are exceptionally peaceful, small, and share their requirement for soft, clean water. They are the absolute perfect, totally harmless algae-cleaning crew for a delicate planted aquascape. Excellent companions include tiny Tetras, Rasboras, peaceful Dwarf Cichlids (like Apistogramma), and small Corydoras. They MUST NEVER be housed with fast, aggressive, or large predatory fish (like Angelfish, Cichlids, or large Barbs) that will easily swallow them whole or bully them away from food.

Aquarium Breeding: Breeding is exceptionally rare, highly rewarding, and typically occurs entirely by accident in perfectly pristine, heavily planted setups. They are continuous egg-scatterers that provide zero parental care. Breeding is triggered by heavy feeding of high-quality greens and massive, cool water changes mimicking the rainy season. The female deposits tiny, highly adhesive eggs individually on the underside of broad leaves or directly on the aquarium glass. The fry are microscopic and require established infusoria and massive amounts of soft algae to survive.

Risks and Diseases: The absolute greatest physical risk is lethal starvation; they are so efficient at eating algae that they will rapidly strip a new tank clean and die within weeks if not heavily supplemented with blanched vegetables and wafers. The tank MUST be mature. The second major risk is severe physiological collapse caused by poor water quality; they are incredibly sensitive to Ammonia spikes. Finally, they are highly vulnerable to being swallowed by larger tankmates due to their tiny size.

Geographic Origin and Distribution

Endemic exclusively to the vast, incredibly complex lower Amazon River basin, specifically heavily concentrated around the pristine, fast-flowing, and highly oxygenated clearwater tributaries near Belém and the Tocantins River in Brazil, South America. Otocinclus hoppei (universally known as Hoppe's Oto or the Dwarf Suckermouth Catfish) natively colonizes the shallow, sun-drenched margins of these rivers. These specific micro-habitats are completely choked with massive, dense forests of submerged aquatic vegetation, thick layers of periphyton (algae), and massive tangles of submerged roots.

Origin

Amazon, Orinoco, and Guianas

Fish profile

Temperament: Peaceful
Diet: Herbivore
Sex ratio: School
Feeding frequency: Continuous
Bioload: Low
Flow: Strong
Jump risk: No
Reproduction: Oviparous
Compatibility & tankmates: Community
Tank level: Middle/Bottom

FishBase

Window to the official scientific data of the species

Data synced on: 06/15/2026

Scientific Parameters & Models

Phylogenetic uniqueness (PD50): 0.5
Bayesian Length-Weight: a = 0.00977, b = 3.06

Image gallery

Licensed images linked to the species or, when marked, to the closest representative taxon.

Related species

Recommendations grouped by close relatives, companion choices, and similar care.

Variants and close relatives

Same atlas type, nearby scientific identity, genus, or family.

Otocinclus (Oto Macrospilus)

Otocinclus macrospilus

Species description

Care, breeding and tankmates

Geographic Origin and Distribution

Origin

Fish profile

Scientific Parameters & Models

Image gallery

Related species

Variants and close relatives

Otocinclus (Oto Macrospilus)

Otocinclus (Oto Vittatus)

Zebra otocinclus

Otocinclus (Dwarf Sucker)

Pitbull pleco

Twig Catfish

Mato Grosso Ancistrus

Magdalena Sand Whiptail

Common Bristlenose Pleco

Bristlenose Pleco (Ancistrus)

Big-Eyed Ancistrus (L144a)

Albino Bristlenose Pleco

Lyretail Pleco

Marble Whiptail

Royal Pleco (L190)

Vampire Pleco (L029)

Recommended companions

Bucephalandra pygmaea "Bukit Kelam / Sintang"

Bucephalandra pygmaea "Kapit"

Bucephalandra sordidula

Bucephalandra sp. "Bodok"

Bucephalandra sp. "Braun-rot narrow"

Bucephalandra sp. "Braun-rot" ("Serimbu")

Bucephalandra sp. "Gunung Sumpit"

Bucephalandra sp. "Kedagang"

Bacopa sp. "Japan"

Bolbitis heteroclita

Ammannia sp. 'Bonsai'

Arrowhead Anubias

Amblystegiaceae sp. "Manaus"

Alternanthera reineckii "rosaefolia minor"

Amazon Sword

Anubias

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