Results for “dimorphism”

This fish belongs to a very distinctive genus of mochokid. There are almost 50 species of Chiloglanis described to science, but most are never imported and even the commoner species, such as this one, are seen only rarely. They are very difficult to identify down to species level, as many are very similar in looks. Some are strongly sexually dimorphic with the males having thickened or enlarged anal and caudal fins. Chiloglanis are also sometimes confused with the other 2 genera of African sucke...

This species is traded under various other names including 'red arc pencilfish', 'Peruvian red pencilfish', 'ruby red pencilfish', 'red pencilfish', and Nannostomus cf. marginatus 'red'. It was initially described as a subspecies of N. marginatus but can be identified by the following combination of characters: pronounced sexual dimorphism with adult males exhibiting bright red pigmentation between the central...

This species has been known in the aquarium hobby since the mid-twentieth century but has almost always been identified as the congener P. deissneri and appears as such in the majority of aquarium literature. It can be told apart from congeners by the colour pattern in adult males (see 'Sexual Dimorphism') plus possession of 11-12 spinous dorsal-fin rays, 13-14 spinous anal-fin rays and 6-8 segmented anal-fin rays.

This species occurs in a couple of colour forms with fish from northern and central Taiwan possessing a greyish base body colour and those from the Linbian river, southern Taiwan having a dark marking in the anterior portion of the first dorsal fin and larger, more intense red spots on the body. The latter form is also smaller in size, lays smaller eggs, does not exhibit extreme sexual dimorphism and has been refe...

Not a commonly species in the aquarium hobby but sporadically available in shipments of wild fishes from Thailand. Following Kottelat (1990) it's a member of a group of species possessing a complete or near-complete lateral line, 8 ½ branched dorsal-fin rays, 17 branched caudal-fin rays and lacking sexual dimorphism (the latter is not strictly true - see above). Its colour pattern is quite distinctive, howe...

The genus Sphaerichthys currently comprises four species with S. osphromenoides by far the best known in the hobby. It's easily distinguishable from the congeners S. vaillanti and S. acrostoma since both exhibit a notably more elongate head and body profile, reverse sexual dimorphism (i.e. females are the more colourful/strongly-patterened), and are paternal mouthbrooders.

This species is not traded commercially at present and the specimen pictured above was brought back from northern Papua New Guinea by private collectors in 2008. It's diagnosable from other members in the genus by possession of 10 segmented rays in the second dorsal fin, males with filamentous spines in the firstandusually with 14 rays. Colour patterning in males is also distinctive (see 'Sexual Dimorphism'). The Gobiidae is the most speciose vert...

As with all members of the genus sexual dimorphism is pronounced. Males are brightly-coloured, with a reddish-orange stripe extending posteriorly from the pectoral-fin, with the posterior portion of the body entirely suffused with red. A darkish band extends from behind the eye to the edge of the opercle, and the basal third of the caudal-fin is reddish-orange.