Records of the Western Australian Museum 17: 29-33 (1995). 
Food of the blind cave fishes of northwestern Australia 
W.F. Humphreys 1 and M.N. Feinberg 2 
'Department of Terrestrial Invertebrate Zoology, Western Australian Museum, Francis Street, Perth, 
Western Australia 6000 
2 Department of Herpetology and Icthyology, American Museum of Natural History, Central Park West at 79th Street 
New York, NY 10024, U.S.A. 
Abstract - Cape Range peninsula, in the arid northwest of Western 
Australia, contains the only cavernicolous fishes in Australasia, both of 
which are considered as vulnerable or endangered. They are associated with 
a stygofauna considered to be of Tethyan origin. Ophisternon candidum (Mees, 
1962) (Synbranchiformes: Synbranchidae) and Milyeringa veritas Whitley, 
1945 (Perciformes: Eleotrididae) occur widely in underground waters and 
are endemic to the peninsula. The gut contents of existing collections were 
examined to elucidate their prey. Both species of troglobitic fish are 
opportunistic in their feeding, able to utilize occasional packets of energy 
entering the stygal realm. 
Ophisternon candidum eats the specialised stygofauna of the region, 
including Halosbaena tulki (Poore and Humphreys, 1992) (Thermosbaenacea) 
and atyid shrimps (Stygiocaris spp.) and also feeds opportunistically on 
aquatic larvae living in the more open part of the subterranean system. The 
biogeographic affinities of O. candidum is in accord with that of its main 
prey. The gut contents constitute the only records of Stygiocaris and 
Halosbaena from Tantabiddy Well (C-26), the type locality of O. candidum. M. 
veritas primarily feeds opportunistically on invertebrates accidentally 
introduced into the aquatic system (mostly terrestrial isopods and 
cockroaches) but also feeds on the stygofauna. 
INTRODUCTION 
The Cape Range peninsula in the arid northwest 
of Australia is noted for its subterranean animals, 
both a terrestrial fauna with wet forest affinities 
(Humphreys 1993a, 1993b, 1993c, 1993d), and an 
aquatic fauna with Tethyan affinities (Humphreys 
1993a, 1993d; Knott 1993). Amongst the latter are 
two species of blind cave fish, the Blind or Cave 
Gudgeon, Milyeringa veritas Whitley, 1945 
(Perciformes: Eleotrididae) and the Blind Cave Eel, 
Ophisternon candidum (Mees, 1962) 
(Synbranchiformes: Synbranchidae). These two 
species of fish comprise the entire vertebrate 
troglobite fauna of Australasia. While other 
stygobiontic fish have been extensively researched 
(e.g. Wilkens 1988), nothing is known of the 
ecology of those inhabiting the Cape Range 
peninsula. 
The Synbranchidae, or swamp eels, are widely 
distributed in tropical and sub-tropical regions. 
They exhibit marked habitat plasticity, being 
predominantly freshwater inhabitants but 
extending into brackish and estuarine waters; the 
same species may occupy a range of epigean 
habitats from streams and lakes to swamps and 
marshes. Swamp and marsh dwellers often show 
amphibious or burrowing habits and many are 
capable of aerial respiration (Rosen and 
Greenwood 1976). 
The genus Ophisternon has a disjunct distribution, 
being found in Australasia, Indo-Malaya, west 
Africa and some island and mainland areas of the 
Caribbean. While the diet of O. candidum has been 
unrecorded previously, synbranchids are 
recognized as nocturnal predators (Moyle and 
Cech 1982). Cavernicolous species, showing 
considerable atrophy of the eye tissue, occur on the 
Yucatan peninsula, Mexico (O. infernale ) (Rosen 
and Greenwood 1976) and in Australia (O. 
candidum). 
The Eleotrididae are widespread in tropical and 
subtropical shallow marine to fresh waters mainly 
in the Indo-Pacific region (Nelson 1984). The 
monotypic genus Milyeringa is endemic to the Cape 
Range peninsula but the phylogenetic relationships 
between members of the family Eleotrididae have 
not been established (see discussion in Knott 1993). 
M. veritas is cavernicolous, eyeless and translucent. 
This species has been considered to feed 
opportunistically upon detritus, algae and 
whatever animals, including insects, accidentally 
fall into the water (Allen 1989). 
Their subterranean habitat restricts observation 
in life and hence very little is known about the 
biology of these fishes. Nonetheless, they have 
respectively been classified as rare and 
recommended for total protection, and vulnerable 
(Michaelis 1985); both fish species as well as two of 
