Presumably inhabits small rivers, tributaries and streams with substrates of gravel, rocks, boulders, and exposed bedrock which undergo seasonal variations in water flow rate, depth and turbidity.

Lanyu Island is volcanic, measures just 45 km² and has no major rivers or large settlements with a permanent human population of around 4000, although there is a large nuclear waste storage facility at its southern end.

This species appears to exist in a number of different forms which exhibit differences in colour pattern, morphology, or both, and it’s currently unclear whether all of them are truly conspecific or not although to avoid confusion we list all together here.

This fish is normally imported alongside the congener R. candidianus and is actually the commoner of the two in the aquarium trade.

It looks very similar to R. candidianus but does not grow as large and possesses a more rounded snout.

Most specimens also have spot-like markings on the sides of the head which has led to them being identified as R. nantaiensis, but the fish do no…

This species is normally imported alongside a smaller-growing, near-identical congener currently listed as R. cf. nantaiensis with both traded as R. candidianus.

They can be separated by snout length, which is noticeably longer in R. candidianus, and adult size with R. cf. nantaiensis reaching just 50-55 mm.

R. candidianus can be distinguished from other congeners by a combination of cha…

This species is almost identical to the wild form of ‘P.‘ semifasciolatus which is best known as the ‘golden barb’ in the aquarium hobby due to the popularity of a yellowish ornamental strain. The natural colour pattern is greenish in both species, however, and in terms of external characters they’re only reliably distinguished by the fact that ‘P.‘ semifasciolatus possesses a pair of prominent maxillary barbels wherea…

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…

This species is a relatively recent addition to the hobby but considering the number of specimens allowed to be collected for scientific research is highly restricted by the Taiwanese Council for Agriculture it seems odd that it's become available at all. Indeed it appears that those in the trade are collected and exported on an illegal basis (T-Y Liao, pers. comm.)…

This species is available occasionally, though not always under the correct name. We've seen it on sale as S. elegans on numerous occasions, for example, and other trade names include 'Sumatran blue neon goby' (it's not found on Sumatra), 'cobalt blue goby' and 'freshwater neon goby'. Further…

This species is rare in the aquarium trade and normally expensive when available. It's one of the most easily-identifiable in the genus by the combination of usually 14 pectoral-fin rays, 10 segmented second dorsal-fin rays, relatively small adult size, unique colouration in males and the shape of the first dorsal-fin in males in which the fourth and fifth spines are…

Butis spp. are largely nocturnal ambush predators with cryptic patterning to help them blend in with their surroundings. They can also lighten and darken their body colouration to an extent, have a habit of aligning themselves with solid surfaces whether horizontal, vertical, or inverted, and often swim in an upside-down position.

The genus is usually included in the family Eleotridae of which members are often referred to…