Hypancistrus seideli

Hypancistrus: from the Greek ὑπό (hypó), meaning 'below, beneath, under', and the generic name Ancistrus, in reference to the reduced dentition compared with the latter.

Collected from the rio Xingu downstream and in the vicinity of Belo Monte, Pará state, northern Brazil.

The majority of its natural habitat is likely to be severely degraded in the near future due to ongoing construction of the Belo Monte dam.

Typically inhabits turbulent stretches of whitewater rapids with rocky substrates.

An aquarium with base dimensions of 120 ∗ 45 cm48 ∗ 18 in or equivalent should be the smallest considered.

Not difficult to maintain under the correct conditions; we strongly recommend keeping it in a tank designed to simulate a flowing stream with a substrate of variably-sized rocks, sand, fine gravel, and some water-worn boulders.

This can be further furnished with driftwood branches, terracotta pipes, plant pots, etc., arranged to form a network of nooks, crannies, and shaded spots, thus providing broken lines of sight.

Like many fishes that naturally inhabit running water it's intolerant to accumulation of organic pollutants and requires spotless water in order to thrive. Weekly water changes of 30-50% tank volume should also be considered routine.

Though torrent-like conditions are unnecessary it does best if there is a high proportion of dissolved oxygen and some water movement in the tank meaning power filter(s), additional powerhead(s), or airstone(s) should be employed as necessary.

Except when juvenile, these prefer a meaty diet. This can consist of live and frozen foods such as bloodworm, chopped mussel and prawn and sinking dried foods. Algae and other vegetable matter is not taken, but the occasional slice of cucumber or courgette might be nibbled at.

A generally peaceful species which can be maintained in a well-chosen community alongside other quiet fishes.

It should not be maintained alongside other Hypancistrus spp. in order to prevent hybridisation.

Males are more slender and less stocky than females, a difference which is easily observed when the fish are viewed from above.

Odontode development is often comparable in both sexes although some older males exhibit more extensive growth on the pectoral fins.

Cave-spawner with the male responsible for brood care. Has been bred regularly in aquaria.

This species, described by Sousa et al. in 2025, is also traded as 'network pleco' and 'scribbled pleco' and has a highly variable colour pattern.

It's regularly confused with similar-looking relatives such as L400, but differs by its less elongate, squatter body shape. Fish traded as L333 are the same species, with a much coarser pattern of pale markings on the body than L066.

The genus Hypancistrus is diagnosed from all other loricariids by a wide separation between the metapterygoid and lateral ethmoid, presence of a sharply angled adductor palatini crest of the hyomandibula, and no lateral wall in the metapterygoid channel.

More useful for aquarists is the fact that in Hypancistrus the dentary teeth are about twice as long as the premaxillary teeth (vs. dentary and premaxillary teeth of approximately equal length).

The genus is otherwise remarkable for the fact that the majority of species have not yet been described to science although many are well known in the aquarium hobby. As of January 2016, there are eight described species in the genus: the type species H. zebra Isbrücker and Nijssen 1991, H. inspector Armbruster 2002, H. contradens Armbruster et al. 2007, H.debiliterra Armbruster et al. 2007, H. furunculus Armbruster et al. 2007, H. lunaorum Armbruster et al. 2007, H. margaritatus Tan & Armbruster 2016 and H. phantasma Tan & Armbruster 2016.