The most common and widespread “black with white spots” Ancistrus from Brazil is this one. It’s a very nice species that is easier to keep and breed than the very similar A.dolichopterus (L183). It has a great potential to establish itself as a popular aquarium fish, but one should keep in mind that it may grow to over 20 cm.
Facts:
Name: Ancistrus sp.
Trade names: Peppermint Ancistrus, L71, L181, L249
Origin: Rio Tapajos, Rio Trombetas, Rio Tefe, Rio Xingu, Rio Cuminá, Rio Manacapuru, Brazil
Maximum TL: 25 cm / 10”
This species has a wide distribution in southern affluents of the Amazon and is a quite hardy and easy to maintain species. It can be bred in neutral tapwater, but it will only thrive in clean, well filtered oxygen rich water. When young, it’s very hard to tell apart from A.dolichopterus (L183) from Rio Negro, since both species have the white edged fins when young. One must look at the dorsal fin and count the rays, L71 has 7-8 soft rays and A.dolichopterus usually has 9. One can also see a pale blue sheen in the white seam of A.dolichopterus which is not visible in L71. More on this can be found in this article by Ingo Seidel: https://www.planetcatfish.com/shanesworld/shanesworld.php?article_id=380
More info:
http://www.l-welse.com/reviewpost/showproduct.php/product/83/cat/44
http://www.planetcatfish.com/common/species.php?species_id=1249