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Ancistrus ranunculus  Muller, Rapp Py-Daniel & Zuanon, 1994

his Ancistrus species is typified by its unusually broad head flattened body and its black body colour. The common name of "Tadpole Bristlenose Catfish" points to this trait of its unusually flat head. The males head bristles are very thick and not branched at the end, unlike most of this genera.
The image below shows the unbranched and thorn shaped head bristles, or tentacles, in this male.

Ancistrus ranunculus

Both sexes have fleshy 'tentacles' but the males are bushier and longer as typified in the picture of a female below. Inhabits clear running water, to a depth of 3 meters during dry season. Prefers narrow cracks of submerged rocks, small passages between superimposed rocks, or lives below flat rocks on the bottom.

In the aquarium you can provide pipe work, flat and rounded stones in a river type setup on a sandy substrate where they will happily reside under as long as the stones are not too heavy. You will also need to provide a good current in the water as they do prefer this and will not do well without it.


A similar species exists, Ancistrus sp. (L255), which also has spots when young but this species holds on to this trait into adulthood whereas A.ranunculus does not.

A broad head and flattened body. Fewer teeth than your average Ancistrus.

Black body colouration with paler white blotches to the body.


No problem with other fishes in the aquarium but due to its liking for a water current you would need to investigate further any species that would be compatable with these conditions.


Unreported in the aquarium as A.ranunculus is not one of the easiest species of Ancistrus to spawn. Should be as per typical of this genera. (See breeding Articles on ScotCat.)

Sexual differences
As with other members of this genus the male sports bristles to the head area, the male having the larger and more impressive tentacles and the female may have shorter bristles.

Likes a meaty diet which is somewhat different from most members of the Ancistrinae. Feed frozen foods such as bloodworm and pellet, tablet and pre-soaked flake.

Ferraris, C.J. Jr., 2007. Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types. Zootaxa 1418:1-628.
Muller, S., L.H. Rapp Py-Daniel and J. Zuanon 1994 Ancistrus ranunculus, a new species of loricariidae fish (Siluriformes: Loricariidae) from the Xingu and Tocantins rivers, Brazil. Ichthyol. Explor. Freshwat. 5(4):289-296.
Seidel, Ingo; Back to Nature guide to L-catfishes 208 p


Ancistrus: With barbed hooks, ( hooked spines)
ranunculus: Meaning "Tadpole" and referring to its unusually flat head.

Photo Credits
Johnny Jensen's Photographic Library
Factsheet 169

Common Name:
Tadpole Bristlenose Catfish, L034.


Brazil Brazil: Xingu and Tocantins River basins. Type locality: Brazil, Pará, Rio Xingú, furo do Tucum Seco, near Arroz Cru. 
14.0cm. ( 5½ins)
26-30°c (79-87°f.)
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                                                                                                                                  Factsheet 169 = updated December 14, 2018 , © ScotCat 1997-2018 Go to Top