Marigold Bristlenose Pleco Care Guide - Aquarium Setup, Diet & Breeding

Marigold Bristlenose Plecos are a golden-yellow colour form of the common bristlenose pleco, Ancistrus cirrhosus. Their compact, flattened bodies, broad heads and armour-like plates give them the classic appearance of a small suckermouth catfish, while their warm yellow to orange colouring makes them especially eye-catching against dark décor.

They are primarily nocturnal and spend much of the day resting on wood, rocks, glass or other surfaces. When active, they use their strong sucker-shaped mouth to graze biofilm and algae, moving steadily around the aquarium rather than swimming continuously in open water.

Adult males develop branched, fleshy bristles across the snout and around the edges of the head. Females may show a few short bristles, particularly when mature, but they usually have a smoother and narrower snout. These facial appendages are a defining feature of mature bristlenose catfish.

In the wild, Ancistrus cirrhosus inhabits slow to moderately flowing streams, tributaries and flooded forest environments. It is an adaptable species with a peaceful temperament, although mature males can be territorial towards one another, especially when competing for spawning caves.

Ancistrus cirrhosus is native to freshwater habitats in tropical South America, particularly the Paraná and Paraguay river systems of Brazil, Paraguay and Argentina. The marigold form is a selectively bred colour variety rather than a separate wild species.

A single Marigold Bristlenose Pleco should be kept in an aquarium of at least 80 litres, with a footprint of approximately 80 cm by 30 cm or larger. Provide efficient filtration, good oxygenation and moderate water movement, while avoiding persistently poor water quality. Use smooth sand or fine rounded gravel, with driftwood, rocks, caves and hardy plants arranged to create shaded retreats. Each male should have access to a suitable narrow cave if more than one is kept. A secure lid is useful, and stable, mature aquarium conditions are preferable to a newly established tank.

Up to about 15 cm (6 in) in total length. Males commonly reach around 12–15 cm (4.7–6 in), while females are often slightly smaller and more lightly built, usually around 10–13 cm (4–5.1 in).

Although they graze algae and biofilm, Marigold Bristlenose Plecos need a varied diet rather than relying on algae alone. Offer sinking algae wafers and vegetable-based catfish foods, supplemented with blanched courgette, cucumber, spinach, kale or shelled peas. They also consume small amounts of animal protein and can occasionally be given sinking foods containing shrimp, insect or other aquatic ingredients. Driftwood should be available as part of their natural grazing environment, and uneaten vegetables should be removed before they decay.

Marigold Bristlenose Plecos are peaceful community fish and can be kept with tetras, rasboras, danios, peaceful barbs, livebearers, dwarf cichlids and other non-aggressive community species. They are also generally compatible with peaceful bottom dwellers, provided there is enough space and shelter. Avoid housing them with aggressive cichlids, fin-nipping species or other territorial bottom-dwellers that may compete for caves. Multiple males require extra room and several separate hiding places.

Marigold Bristlenose Plecos are cave-spawning catfish that can breed readily when mature males and females are provided with suitable shelter. The male selects and cleans a narrow cave, where the female deposits a cluster of adhesive eggs. He guards and fans the eggs until they hatch, usually in around 5–10 days, and the fry absorb their yolk sacs over the following few days. Once free-swimming, the young can be offered soft vegetables, algae-based foods and finely crushed prepared foods. Males may fight over caves, so each breeding male should have access to a separate shelter.

Mature males develop prominent branched bristles on the snout and along the front of the head, whereas females usually have a smoother face with few or no substantial bristles. Males are generally larger and broader-headed, while females tend to have a rounder abdomen when carrying eggs.