Indostomus crocodilus

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Indostomus crocodilus
Systematics
Spinefish (Acanthopterygii)
Perch relatives (Percomorphaceae)
Order : Gill slit eels (Synbranchiformes)
Family : Indostomidae
Genre : Indostomus
Type : Indostomus crocodilus
Scientific name
Indostomus crocodilus
Britz & Kottelat , 1999

Indostomus crocodilus ( Latin crocodilus - crocodile) is one of two species of the fish genus Indostomus, which had been monotypical until then, that were newly described in 1999. Even before it was first described, the species wasexported from Thailandby the aquarium trade from 1994 onwards, and individual specimens had already reached Europe through individual imports by aquarists. These fish were, however, attributedto Indostomus paradoxus , therefore some older publications on the reproduction of I. paradoxus in captivity probably refer to the species described here. The specific epithet is intended to indicate the crocodile -like appearance.

distribution and habitat

The holo- and paratypes come from a black water river in the Thai province of Narathiwat . The animals were caught between underwater plants close to the ground.

Appearance

I. crocodilus remains very small and only reaches a standard length of about 2.5 centimeters. The body is covered with bony plates covered with jagged ridges, the arrangement of which corresponds to that of the other two generic representatives, I. paradoxus and I. spinosus . On the back there are 21 occasionally 22 shields, the sides and belly are covered by 22, or more rarely 23, plates. As with the other Indostomus , jagged bone ridges extend over the head and shoulder girdle, but less strongly toothed than in I. spinosus and with more pronounced teeth than in I. paradoxus . The rear edge of the gill cover ends in six or seven points that grow larger from bottom to top. The top five or six of these are each at the end of a jagged ridge that runs over the gill cover. There are four to five spines in front of the dorsal fin with soft rays . The outer rays of the pectoral fins of the male fish are curved and longer than the almost straight fin rays of their female counterparts.

In addition to the differently pronounced ornamentation on the head and shoulder girdle, I. crocodilus also distinguishes itself from its close relatives by the coloring. In contrast to I. spinosus, the ventral side and in particular the underside of the head are lighter colored. Adult males also have distinct dark brown to black stripes on their dorsal and anal fins , which the male I. paradoxus either completely lack or are only weakly developed in sexually active males.

Fins formula : dorsal IV – V / 6, anal 6, pectoral 22–24, ventral 4, caudal 12

supporting documents

  1. ↑ a b c d e Ralf Britz, Maurice Kottelat: Two new species of gasterosteiform fishes of the genus Indostomus (Teleostei: Indostomidae) . In Ichthyological Exploration of Freshwaters . Volume 10, No. 4, 1999, ISSN  0936-9902 . P. 333

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