Please note the following sections of the article: "The species being discussed are defined as those ?that are suitable for unheated aquariums kept in centrally heated rooms only. They are not suitable for unheated aquaria in colder rooms"
"In general we would not recommend any species that cannot easily tolerate temperature below 17?C to be kept in unheated aquaria."
Just in case the link breaks the following lists are included:
"Species that we consider to be unsuitable for aquaria without heaters include: - Common platy (Xiphophorus maculates) - Guppies (Poecilia reticulata) - Southern American corydoras (Corydoras sp.) - Siamese fighting fish (Betta splenden)"
"Suitable species include: - American-Flag Fish (Jordanella floridae) - Medaka (Oryzias latipes) - Paradise Fish (Macropodus opercularis) - Rosy Barb (Puntius conchonius) - Variegated platy (Xiphophorus variatus) - White cloud mountain minnow (Tanichthys albonubes) - Zebra danio (Danio rerio)"
Re: Keeping temperate fish in unheated aquaria.
Hillstream loaches and gobies require rather high levels of flow which new fishkeepers might find daunting so as long as this is borne in mind yeah I'd agree as they are much happier at lower tank temperatures.