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his is certainly a catfish for the most avid catfish enthusiast and not a species you can take lightly and introduce to your community tank as this character will make short work of any smaller fishes but would be a good candidate for a large aquarium of 6' 0" (180cm) or bigger. We are of course talking about the Pac-Man Catfish, aka, Lophiosilurus alexandri.

 

Lophiosilurus alexandri

 

Lophiosilurus is similar to Pseudopimelodus but the head is very large and flattened and is the only species in this genera. Dorsal fin short and the caudal fin is rounded. The juveniles look similar to the Chaca genera from Asia and like them are very predatory.

There are a few discussions on the meaning of the common name of "Pac-Man catfish" but the most popular seems to refer to the big mouth that is wide and long, and relates to the monsters of the Arcade game from the eighties. This is a species for the aquarist with an acquired taste as It will find Lophiosilurus alexandri covered in sand most of the time.

 

 

Lophiosilurus alexandri - head view

 

Lophiosilurus alexandri have been bred under laboratory conditions and they, experience impressive changes in body shape during development, becoming extremely depressed when fully developed. It is an ideal species to observe the morphological changes during ontogeny, and to seek solid interpretations on the polarity of characters. Changes in body shape, position of mouth and eye, morphology of fins and pigmentation were observed during the development of Lophiosilurus. Larvae (5.7–11.2 mm standard length) had pigmentation concentrated on the head and parts of body, eyes small and pigmented, short barbels, and well-developed finfold. Juveniles (15.9–28.1 mm standard length) had body shape similar to adult, with head depressed and bearing bony ridges, large mouth, dorsally-oriented eyes, small barbels and well-developed shoulder bulges (cleithral width). The greatest morphological changes in the development of L. alexandri occurred during the postflexion larval stage. Relative to standard length, measurements of snout length, head depth and body depth are smaller in juveniles than in larvae, but body width is larger. New interpretations on the phylogenetic characters related to these changes are provided in view of the two alternative hypotheses of the evolution of Pseudopimelodidae. (Assega FM et al. 2016). For further reading search for Assega FM, Birindelli JLO, Bialetzki A, Shibatta OA (2016) External Morphology of Lophiosilurus alexandri Steindachner, 1876 during Early Stages of Development, and Its Implications for the Evolution of Pseudopimelodidae (Siluriformes).

 

Lateral view of larvae of Lophiosilurus alexandri: a) newly hatched, MZUEL 5725; b) one-day old, MZUEL 5681

 

 

Lophiosilurus alexandri 17 days after hatching, MZUEL 5686, early mid-stage of postflexion: a) lateral view; b) dorsal view of anterior region; c) left pectoral fin in dorsal view

 

 

 

Lophiosilurus alexandri juvenile, 60 days after hatching, MZUEL 5694: a) lateral view; b) dorsal view of head; c) dorsal view of left pectoral fin. Small dorsal and ventral procurrent rays not visible

 

Pac-Man Catfish

Lophiosilurus agassizi, Pseudopimelodus agassizi

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South America: São Francisco River basin. Type locality: Aus Brasilien, wahrscheinlich aus dem Amazonenstrome.

70cm. (28ins)

22-27°C (71-81°F)

Very large and flattened head. Occipital process meets the predorsal plate. The eyes are minute and the maxillary and postmental barbels extend only to the posterior margin of the orbit. The gape of the mouth is oblique and the lower jaw projects. Both margins of the pectoral spines are serrated. Dorsal fin is short and the caudal fin is rounded.

Sandy coloured all over with small dark spots.

Not to be kept with fish that are too small as they will be eaten, better to be kept on their own or with large non-aggressive species. Would need a large aquarium as this species grows to 70cm. (28ins) SL.

Large yolk sac persistent on day 4, much reduced at day 9, and completely consumed within the 13th day of development. Non-migratory and its reproduction involves the construction of a circular nest depression (40–50 cm diameter and 8–10 cm depth) in a shoal area. Spawning is parceled and the female lays large adhesive eggs (3.1 to 3.6 mm) in the center of the nest, which are then guarded and maintained by the male. Upon hatching, the larvae remain at the bottom of the nest and do not move vertically into the water column.

Not known.

Live foods such as earthworms and frozen foods.

Lateral line: A sensory line, along the sides of the body.
Caudal fin: Tail
Dorsal fin: The primary rayed fin(s) on top of the body.
Pectoral: The paired fins just behind the head.
Cleithral: The major bone of the pectoral girdle, extending upward from the pectoral fin base and forming the rear margin of the gill cavity, also: the principal bow-shaped bone of the prectoral girlde, dermal in origin, forming the rear margin of the gill cavity. It articulates dorsally with the supracleithrum and ventrally with the scapula and coracoid.
Occipital: A median bone on the upper surface of the back of the head; pertaining to the occiput.

Lophiosilurus: Greek, lophos = crest + Greek, silouros = cat fish.

Burgess, W.E., 1989. An atlas of freshwater and marine catfishes. A preliminary survey of the Siluriformes. T.F.H. Publications, Inc., Neptune City, New Jersey (USA). 784 p.
Assega FM, Birindelli JLO, Bialetzki A, Shibatta OA (2016) External Morphology of Lophiosilurus alexandri Steindachner, 1876 during Early Stages of Development, and Its Implications for the Evolution of Pseudopimelodidae (Siluriformes). PLoS ONE 11(4): e0153123.
Froese, R. and D. Pauly. Editors. 2019.FishBase. World Wide Web electronic publication. www.fishbase.org, ( 12/2019 ).

Photo Credits

Lophiosilurus alexandri © Addron
Map: Google maps 2020
Wikipedia Commons: Map, Shannon1, 2020.