Lepidogalaxias salamandroides
FAMILY
Lepidogalaxiidae
TAXONOMY
Lepidogalaxias salamandroides Mees, 1961. Tiny creek about 6 mi (9.6 km) east-northeast of Shannon River, Western Australia.
OTHER COMMON NAMES
English: Shannon mudminnow; German: Salamanderfisch.
PHYSICAL CHARACTERISTICS
Length about 2.9 in (7.5 cm), small, elongate; dorsal fin posteriorly placed. Scales absent on head, back, and belly. Pelvic fins well developed, even at hatching. Males have enlarged anal fin sheathed with scales. Brown to gray overall, dark saddlelike markings dorsally, and blotches laterally, the latter forming a pair of stripes during breeding.
DISTRIBUTION
Restricted to a small area of peat flats on the southern coast of Western Australia. Used to extend from Margaret River in the west (about 186 mi/300 km) south of Perth) to Albany in the east; in 2003 its range had contracted to central 93–125 mi/150–200 km) of this area.
HABITAT
Fresh waters in streams, ponds, and shallow pools. Most common in ephemeral, tannin-stained, highly acidic (pH 3.0) pools that can exceed 95°F (35°C) in summer. Solitary and benthic, rests on pelvic fins amid riparian vegetation and in open waters. Larvae and juveniles most common in very shallow water (less than 3.9 in/10 cm), tend to move into deeper waters (usually less than 39.4 in/1 m) as they grow.
BEHAVIOR
Exhibits several behaviors rare among fishes. Like lungfishes, estivates when pools in which they live become dry, burrowing into the substrate, forming an "S" shape, and producing a mucous cocoon, emerging when pools refill with winter rain. Unlike black-striped minnow, buries itself before the pool becomes almost dry.
FEEDING ECOLOGY AND DIET
Active carnivore at all stages, feeds on small crustaceans and insect larvae. Individuals rest on the substrate with their head and body raised up, supported by the large pelvic fins present at hatching. Unlike any other species of fishes, salamanderfish have very large gaps between the vertebrae immediately behind the head. These gaps allow them to move their head from side to side when scanning for prey, which is crucial, as muscles that allow movement of the eyes are absent or greatly reduced. When prey are within about half a body length, darts forward, engulfing and swallowing prey whole.
REPRODUCTIVE BIOLOGY
About 27% attain sexual maturity and spawn at the end of the first year, when males are 1.5 in (3.9 cm) and females are about 1.7 in (4.3 cm). All two-year-old fishes mature and spawn. Each individual spawns several times between late May and late August, peak activity in late July/early August. Mean number of mature eggs is approximately 82; diameter is 0.07 in (0.18 cm). Many fish survive to spawn in two seasons, but only a few survive to spawn at the end of the third and fourth years. Spawning behavior is unique. Males develop an enlarged anal fin surrounded by a sheath of scales. On finding a receptive female, a male will approach and nudge her sides, if she does not swim away or react aggressively, he will approach from the side, and using his scale sheath grasp the female around her anal fin and cloaca. Sperm is introduced into the female via his enlarged anal fin. In the laboratory, males may remain attached to a female for several hours. When physically removed, a male always reattaches from the same side; apparently, just like humans, salamanderfish are either right or left "handed."
CONSERVATION STATUS
Not listed by the IUCN. Regarded as vulnerable by the Australian Society for Fish Biology.
SIGNIFICANCE TO HUMANS
None, although the Western Australian Department of Fisheries and commercial breeders of ornamental fishes are considering its suitability as an aquarium fish.
