Luciosoma bleekeri

Luciosoma: from the Latin lucius, meaning 'a fish (probably the pike)', and Ancient Greek σῶμα (sôma), meaning 'body', in reference to the elongate, pike-like body shape in members of this genus.

bleekeri: in honour of Dutch medical doctor and ichthyologist Pieter Bleeker (1819-1878), who proposed this genus in 1855.

Native to the Mekong River in Laos, Thailand, Cambodia, and Vietnam, plus the Chao Phraya and Mae Klong systems in central and western Thailand, respectively. In the Mekong basin records exist from various major tributary systems including the Mun, Xe Don, Srepok, Sesan, and Tonlé Sap drainages.

Type locality is 'Meinam River near Bangkok', which corresponds to the Chao Phraya River at Bangkok, Thailand.

A riverine species displaying a preference for flowing water, but also moves into areas of swampland and inundated forest during the wet season (June to September) and migrates back to perennial waters from November to December.

An aquarium with surface dimensions of 240 ∗ 60 cm96 ∗ 24 in or equivalent should be the smallest considered.

Choice of decor is not as critical as water quality and the amount of open swimming-space provided, although it is likely to thrive in an aquarium set up to resemble a flowing stream or river with a substrate of variably-sized, water-worn rocks, sand, fine gravel and perhaps some small boulders.

This can be further furnished with driftwood roots or branches, and while the majority of aquatic plants will fail to thrive in such surroundings hardy types such as Microsorum, Bolbitis or Anubias spp. can be grown attached to the décor.

Though very fast flow is unnecessary it should also prefer a relatively high proportion of dissolved oxygen and moderate water movement. Weekly water changes of 30-50% volume should also be considered routine, and the tank must have a very tightly-fitting cover as all Luciosoma spp. are accomplished jumpers.

The major proportion of this species' natural diet is composed of terrestrial insects which are captured at the water surface, although presumably it also feeds on aquatic invertebrates, fish fry and suchlike.

Sexually mature females are likely to be deeper-bodied than males.

Luciosoma species are only suitable for the largest private aquaria, although subadults of L. setigerum, L. bleekeri, and an unidentified fish with a distinctive colour pattern (see below) are traded on a regular basis. They are mostly marketed as 'apollo shark', 'shark minnow', or similar, and often labelled with incorrect scientific names.

Luciosoma spilopleura is used very commonly, for example, but that species may never have been collected for aquaria. Similarly, L. pellegrinii is scarcely known in the aquarium trade since it is native to an area where very few commercial collections take place, but its name is misapplied on a regular basis.

The five species which currently comprise Luciosoma can be identified by elements of colour pattern. L. bleekeri is most-easily distinguished from the congener L. setigerum, with which it is frequently confused, by absence (vs. presence) of a series of black spots on the lateral line scales.

It can be distinguished from other members of the genus by the following combination of characters: dark lateral body stripe typically composed of interconnected spots and extended into a black blotch at the base of the upper caudal-fin lobe; caudal-fin with numerous dark spots; no spots on lateral line scales; barbels well-developed.

There is a fish of unknown geographical origin which matches the majority of diagnostic features for L. setigerum with the exception that the dark lateral stripe is absent in the anterior portion of the body and is not composed of interconnected spots. It is relatively common in the aquarium trade and referred to here on SF as L. cf. setigerum until a confirmed identity is established. Images are available on the L. setigerum profile page.