Crazy fish Butis butis, copyright BEDO.

Belongs within: Gobiomorpharia.

The Butidae are a family of gobies bearing six branchiostegal rays supported by molecular data.

Fishes be crazy
Published 5 May 2016

Despite how it may look, there is absolutely nothing wrong with this fish. Butis butis is a moderately sized species of fish (up to about 14 cm in length) widespread in warmer waters around the Indian and western Pacific Oceans. They are found in shallow bays and mangrove swamps, often entering into estuaries and lower reaches of rivers. It is known by a range of vernacular names, including crimson-tipped gudgeon or duckbill sleeper. In the aquarium trade, it often goes by the name of crazy fish, in reference to its distinctive habit of swimming hanging vertically head-down or even swimming upside-down. Its predilection for such unusual angles assists it in remaining concealed from both predators and prey; Ryan (1981) noted that the addition of anaesthetic for collection purposes to a pool resulted in the sudden appearance of several specimens of which no sign had been previously seen. Their camouflage abilities are further enhanced by the ability to change colour to a certain degree, from pale to dark. Butis butis are ambush predators of smaller fish and invertebrates that they engulf in their broad jaws with rapid lunges.

Drawing of Butis butis, coloured from an original in Herre (1927) by M. L. Nievera.

The genus Butis belongs among the gobies, a somewhat notorious group of fish from a taxonomic perspective. In the words of the South African ichthyologist J. L. B. Smith, “The Gobioid fishes are one of the major trials of ichthyologists, and when general regional collections are worked up, these fishes tend to be pushed aside, and are apparently often identified with some impatience by those not specially interested” (Smith 1958). This notoriety is mostly due to the small size of many gobies, together with a tendency to the reduction of diagnostic features. Earlier authors classified Butis within the Eleotridae, a group of gobies (commonly known as sleepers, presumably due to their benthic habits) distinguished by having the pelvic fins separate from each other (in other gobies, the pelvic fins are united into a ventral sucker or disc). This, however, is a primitive feature only, and more recent molecular phylogenies have confirmed the paraphyly of Eleotridae in the broad sense. As a result, Butis and some of its nearest and dearest have been separated out into a separate family Butidae (Thacker 2011). However, while the separation of Eleotridae and Butidae seems to be fairly widely accepted, the two groups are still not clearly defined morphologically. Characteristic features of Butis relative to other gobies include (among others) the presence of a complete covering of scales, and a bony ridge above each eye (Smith 1958). In a number of species of the genus, including B. butis, the head is low and long, and the lower jaw distinctly protruding; however, the mudsleeper B. koilomatodon has a shorter, rounder head (this latter species, though originally native to a similar range to B. butis, has become invasive in more recent years in west Africa and Brazil, presumably carried in ballast water). Butis butis differs from other species in the genus in having small secondary scales at the base of most scales on the trunk, and the bony ridges above its eyes are more or less smooth (Herre 1927).

Systematics of Butidae
<==Butidae [Butinae]T11
    |  i. s.: IncaraT11
    |         Prionobutis Bleeker 1874T11, MWW89
    |           `--*P. dasyrhynchus (Gunther 1868)S58 [=Eleotris dasyrhynchusMWW89]
    |         Typhleotris Petit 1933T11, TP86
    |           |--T. madagascariensis Petit 1933TP86
    |           `--T. pauliani Arnoult 1949TP86
    |--Butis Bleeker 1856T09, MWW89 [incl. Themistocles Whitley 1939MWW89]
    |    |--*B. butis (Hamilton-Buchanan 1822)MWW89 (see below for synonymy)
    |    |--B. amboinensis (Bleeker 1853) [=Eleotris amboinensis]MWW89
    |    |--B. gymnopomus (Bleeker 1853) [=Eleotris gymnopomus]MWW89
    |    |--B. humeralis (Valenciennes 1837)YK06, S58 [=Eleotris humeralisS58]
    |    |--B. koilomatodon (Bleeker 1849) (see below for synonymy)MWW89
    |    |--B. melanostigma (Bleeker 1849) [=Eleotris melanostigma]MWW89
    |    `--B. prismaticus (Bleeker 1849) [=Eleotris prismaticus]MWW89
    `--+--+--Kribia nanaT09
       |  `--‘Oxyeleotris’ nulliporaT09
       `--+--Oxyeleotris Bleeker 1874T09, H27
          |    |  i. s.: O. fimbriatus (Weber 1908)AC90 (see below for synonymy)
          |    |         O. heterodon (Weber 1908) [=Eleotris heterodon; incl. Boroda malua Herre 1935]AC90
          |    |         O. urophthalmus (Bleeker 1851) (see below for synonymy)M58
          |    |--O. marmorata (Bleeker 1852)T09, H27 [=Eleotris marmorataH27]
          |    `--+--O. lineolatus (Steindachner 1867)T09, M58 [=Eleotris lineolatusM58; incl. E. immaculatus Macleay 1884M58]
          |       `--O. selheimi (Steindachner 1867)T09, M10
          `--+--Bostrychus Lacépède 1802T09, H27 [incl. Bostrichthys Duméril 1806H27]
             |    |--B. africanusMWW89
             |    |--B. sinensis Lacépède 1802M58 (see below for synonymy)
             |    |--B. strigogenys Nichols 1937 [=Bostrichthys strigogenys]M58
             |    `--B. zonatus Weber 1908 [=Bostrichthys zonatus]M58
             `--Ophiocara Gill 1863T09, S58
                  |--*O. ophiocephalus (Valenciennes 1837)S58 (see below for synonymy)
                  |--O. aporos (Bleeker 1854)S58 (see below for synonymy)
                  |--O. macrolepidotus (Bloch 1792) [=Sciaena macrolepidota, Eleotris macrolepidotus]M58
                  `--O. porocephala (Valenciennes 1837)S58 (see below for synonymy)

Bostrychus sinensis Lacépède 1802M58 [=Bostrichthys sinensisM58, Eleotris sinensisH27, Philypnus sinensisH27; incl. P. ocellicauda Richardson 1844H27]

*Butis butis (Hamilton-Buchanan 1822)MWW89 [=Cheilodipterus butisMWW89, Eleotris butisMWW89; incl. Butis leucurus Jordan & Seale 1905H27, E. melanopterus Bleeker 1852S58]

Butis koilomatodon (Bleeker 1849) [=Eleotris koilomatodon, Prionobutis koilomatodon; incl. E. caperatus Cantor 1850, Butis caperatus, E. caperata, E. delagoensis Barnard 1927, Prionobutis serrifrons Rutter 1897, Butis serrifrons, P. (*Themistocles) wardi Whitley 1939]MWW89

Ophiocara aporos (Bleeker 1854)S58 [=Eleotris aporosS58, Ophieleotris aporosAC90; incl. Ophiocara aporos var. guntheri Koumans 1937M58, Eleotris hoedtii Bleeker 1854M58, Ophiocara aporos hoedtiiM58, E. kuak Thiollière 1857M58, E. (Giurus) laglaizei Sauvage 1880H27, Ophiocara laglaiziJR10, O. aporos rigonis Whitley 1938M58]

*Ophiocara ophiocephalus (Valenciennes 1837)S58 [=Eleotris ophiocephalusS58; incl. E. tumifrons Cuvier & Valenciennes 1837O97]

Ophiocara porocephala (Valenciennes 1837)S58 [=Eleotris porocephalaS58, O. porocephalusH27; incl. E. aporocephalus Macleay 1884O97, E. cantoris Günther 1861H27, Agonostoma darwiniense Macleay 1878M58, Ophiocara darwiniensisM58, O. porocephala var. darwinienseM58, Eleotris limosus Smith 1936S58, O. limosusS58, E. madagascariensis Valenciennes 1837S58, E. porocephaloides Bleeker 1853H27]

Oxyeleotris fimbriatus (Weber 1908)AC90 [=Eleotris fimbriatusAC90; incl. E. (Oxyeleotris) aruensis de Beaufort 1913M58, E. (O.) urophthalmoides Weber 1908M58]

Oxyeleotris urophthalmus (Bleeker 1851) [=Eleotris urophthalmus; incl. O. urophthalmus var. novaeguineae Koumans 1936]M58

*Type species of generic name indicated


[AC90] Allen, G. R., & D. Coates. 1990. An ichthyological survey of the Sepik River, Papua New Guinea. Records of the Western Australian Museum Supplement 34: 31–116.

[H27] Herre, A. W. 1927. Gobies of the Philippines and the China Sea. Bureau of Printing: Manila.

[JR10] Jordan, D. S., & R. E. Richardson. 1910. Check-list of the species of fishes known from the Philippine archipelago. Bureau of Printing: Manila.

[MWW89] Miller, P. J., J. Wright & P. Wongrat. 1989. An Indo-Pacific goby (Teleostei: Gobioidei) from West Africa, with systematic notes on Butis and related eleotridine genera. Journal of Natural History 23: 311–324.

[M10] Morgan, D. L. 2010. Fishes of the King Edward River in the Kimberley region, Western Australia. Records of the Western Australian Museum 25 (4): 351–368.

[M58] Munro, I. S. R. 1958. The fishes of the New Guinea region: a check-list of the fishes of New Guinea incorporating records of species collected by the Fisheries Survey Vessel “Fairwind” during the years 1948 to 1950. Papua and New Guinea Agricultural Journal 10 (4): 97–369 (reprinted: 1958. Territory of Papua and New Guinea Fisheries Bulletin no. 1).

[O97] Ogilby, J. D. 1897. On some Australian Eleotrinae. Proceedings of the Linnean Society of New South Wales 21 (4): 725–757.

Ryan, P. A. 1981. Records of three new freshwater fishes from the Fiji Islands. Pacific Science 35 (1): 93–95.

[S58] Smith, J. L. B. 1958. The fishes of the family Eleotridae in the western Indian Ocean. Ichthyological Bulletin 11: 137–163.

[T09] Thacker, C. E. 2009. Phylogeny of Gobioidei and placement within Acanthomorpha, with a new classification and investigation of diversification and character evolution. Copeia 2009 (1): 93–104.

[T11] Thacker, C. 2011. Systematics of Butidae and Eleotridae. In: Patzner, R. A., J. L. Van Tassell, M. Kovačić and B. G. Kapoor (eds) The Biology of Gobies pp. 79–85. CRC Press.

[TP86] Thinès, G., & G. Proudlove. 1986. Pisces. In: Botosaneanu, L. (ed.) Stygofauna Mundi: A Faunistic, Distributional, and Ecological Synthesis of the World Fauna inhabiting Subterranean Waters (including the Marine Interstitial) pp. 709–733. E. J. Brill/Dr. W. Backhuys: Leiden.

[YK06] Yokoo, T., K. Kanou, M. Moteki, H. Kohno, P. Tongnunui & H. Kurokura. 2006. Juvenile morphology and occurrence patterns of three Butis species (Gobioidei: Eleotridae) in a mangrove estuary, southern Thailand. Ichthyological Research 53: 330–336.

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