Adonis Pleco
Acanthicus adonis
Loricariidae
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About
Described from the lower rio Tocantins at Cametá in Pará, Brazil, and probably ranging much further through the Amazon, this is the giant of the pleco world. Juveniles are pitch black under a scatter of white polka dots, with a deeply forked, lyre-shaped tail drawn out into long filaments; the spots shrink and vanish with age until a big fish is plain black armour bristling with sharp odontodes, its pectoral fins alone over 15 cm long. Shops sell it at 8 cm, but PlanetCatfish and Seriously Fish both put the adult at up to 1000 mm SL. Juveniles are calm; adults are combative regardless of sex, claim every cave in the tank and have been recorded killing large plecos that failed to move aside. It is traded worldwide as L155, although PlanetCatfish — the L-number authority — reserves that code for its smaller relative Acanthicus hystrix.
Care
Treat the 400 L figure implied by juvenile sales as fiction: this fish reaches 60–100 cm and honestly needs a custom 2000 L+ tank or indoor pond with a footprint of at least 300 x 100 cm, and Seriously Fish puts a full adult at base dimensions beyond 600 x 200 cm. One specimen per tank, and never alongside other big plecos such as Pseudacanthicus. Inert sand, bogwood and rockwork too heavy to shove, dim light, brisk flow, very high dissolved oxygen (it cannot gulp air) and filtration sized for a koi pond. Adults eat or uproot plants. Move it in a solid container, never a net — the odontodes are sharp and snag instantly.
Diet
Offer sinking wafers and large catfish pellets as the base, plus courgette, cucumber and fruit, and add meaty items several times a week: prawns, mussels, cockles, earthworms and pieces of fish. Keep a large piece of bogwood available for grazing. Feed generously — sunken bellies and eyes on shop juveniles mean the fish is already starving — and expect to match the feeding with heavy water changes.
Tankmate compatibility
Avoid (271)
Computed by the AquaSage engine for a spacious reference tank — always check the full verdict for your exact setup in the calculator.
Telling males from females
What works for this species, most reliable first.
- Bristles and cheek spinesStrong · from about a year
Male plecos grow odontodes — spiny growths on the cheeks and along the leading pectoral rays. Bristlenose males additionally grow branching tentacles across the snout and over the top of the head.
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Frequently asked questions
- What tank size does a Adonis Pleco need?
- A Adonis Pleco needs an aquarium of at least 2000 litres (528.3 US gallons) with a footprint at least 300 cm (118.1 in) long — for this species, swimming length matters as much as raw volume.
- What water parameters does a Adonis Pleco need?
- Adonis Pleco does best at 23–30 °C (73.4–86 °F), pH 6–7.5 and a general hardness of 2–12 °dGH.
- Is the Adonis Pleco suitable for beginners?
- Adonis Pleco is a demanding species best attempted with some experience — it needs stable, closely watched conditions to thrive.