Records of the Western Australian Museum 17:117 (1995). 
Short communication 
Inability of salamanderfish, Lepidogalaxias salamandroid.es, 
to tolerate hypoxic water 
Tim M. Berra 1 and Gerald R. Allen 2 
1 Department of Zoology, Ohio State University, Mansfield, Ohio 44906, U.S.A. 
2 Department of Aquatic Vertebrates, Western Australian Museum, Francis Street, Perth, Western Australia 6000 
The salamanderfish, Lepidogalaxias salamandroides, 
is the sole member of the Osmeriform family 
Lepidogalaxiidae and is only found in the 
southwest corner of Western Australia. The 
preferred habitat of this small (maximum SL 67 
mm) fish includes freshwater pools that evaporate 
during the summer (Allen and Berra 1989). 
Salamanderfish survive the desiccation of their 
habitat by burrowing into the damp substrate and 
remaining moist as the groundwater retreats from 
the surface. The fishes emerge from the bottom 
within minutes after autumn rains partially fill the 
dry pools (Berra and Allen 1989). 
A recent study demonstrated that salamanderfish 
have the ability to exchange 0 2 and C0 2 through 
their skin while out of water as long as they remain 
moist. Martin et al. (1993) showed that during 
aerial respiration an average of 83% of the V0 2 and 
69% of the VC0 2 exchange took place across the 
posterior cutaneous surfaces. This high level of 
cutaneous respiration confirms that the 
swimbladder is not used as an accessory aerial 
respiratory structure (Berra et al. 1989). 
In order to determine if salamanderfish have any 
special ability to tolerate low 0 2 conditions in 
water the following experiment was conducted at 
the Western Australian Museum in October 1988 
with newly collected salamanderfish from Station 
22 (Berra and Allen 1989) and other species from a 
nearby stream. 
Nitrogen gas was bubbled through 11 of 
aquarium water at 19°C via an air stone at a 
pressure of less than 3 psi in order to remove 
dissolved oxygen. Four trials were run, in which L. 
salamandroides (N=6, xSL = 30 mm) was compared 
with three other fish species (Edelia vittata (N=l, SL 
=34 mm), Galaxias occidentals (N=3, xSL=70 mm), 
and Galaxiella nigrostriata (N=6, xSL=28)). A 
polarographic oxygen probe connected to an air- 
calibrated ICM type 30 oxygen meter (accuracy: ± 
2%) was immersed in the water, and the dissolved 
oxygen levels were recorded. The reactions of the 
fishes were observed; when they exhibited signs of 
ataxia, they were removed to fresh oxygenated 
water. 
Dissolved 0 2 at the beginning of each experiment 
was 6-7 ppm. The fishes swam normally or sat on 
the bottom in the case of Lepidogalaxias until 0 2 
levels reached approximately 1.0 ppm. In most 
cases this occurred within 5 minutes. At 1 ppm, all 
fishes began leaping and gulping air at the surface. 
Approximately 2-3 minutes after the 0 2 tension 
reached 0.8 ppm all species became ataxic. They 
lost the ability to right themselves and lay on their 
sides on the bottom. At this point the fishes were 
removed to fresh aerated water. All recovered and 
were swimming normally within a few minutes. 
There was no noticable difference in the reaction of 
Lepidogalaxias and the other species. The smallest 
fish of each species was the first to succumb; 
Galaxiella appeared to tolerate the low pO z slightly 
longer than the other 3 species. 
We conclude that salamanderfish have no special 
ability to tolerate hypoxic water. The ability to 
survive in their ephemeral habitat depends upon 
burrowing into the substrate and remaining damp 
on the water table below the surface during times 
of drought. During this time the fish presumably 
enter a lowered metabolic state and respire 
cutaneously. The nature of this aestivation and 
what environmental cues trigger it remain to be 
determined. 
ACKNOWLEDGEMENT 
We thank Clay Bryce for technical assistance with 
the nitrogen apparatus. 
REFERENCES 
Allen, G. R. and Berra, T. M. (1989). Life history aspects 
of the west Australian salamanderfish, Lepidogalaxias 
salamandroides Mees. Records of the Western Australian 
Museum 14: 253-267. 
Berra, T. M. and Allen, G. R. (1989). Burrowing, 
emergence, behavior, and functional morphology of 
the Australian salamanderfish, Lepidogalaxias 
salamandroides. Fisheries 14(5): 2-10. 
Berra, T. M. Sever, D. M. and Allen, G. R. (1989). Gross 
and histological morphology of the swimbladder and 
lack of accessory respiratory structures in 
Lepidogalaxias salamandroides, an aestivating fish from 
western Australia. Copeia 1989: 850-856. 
Martin, K. L. M., Berra, T. M. and Allen, G. R. (1993). 
Cutaneous aerial respiration during forced 
emergence in the Australian salamanderfish, 
Lepidogalaxias salamandroides. Copeia 1993: 875-879. 
Manuscript received 17 September 1993; accepted 6 May 1994. 
