The Australian grayling (Prototroctes maraena) is a primarily freshwater fish found in coastal rivers in south-eastern mainland Australia and Tasmania.

[2] The species was appreciated for its willingness to take wet and dry flies, its excellent fighting ability on very light tackle, and its relatively large size.

So virulent and exhaustive was this epidemic that many, more especially of the southern rivers, were more or less completely denuded of their stock of this species and have so remained up to the present date".

Saville-Kent posed the questions of how, when and where the epidemic originated and whether at the time there were any abnormal conditions associated with the rivers carrying the infected fish.

Under such conditions the germs or spores, like the microbes of measles or smallpox, arriving on a virgin and congenial soil, might be expected to spread with devastating virulence among the aboriginal inhabitants.

[7] A chronic lack of alien-trout-free habitat reserved for galaxias, grayling and other native fish species in south-eastern Australia generally is a major concern.

Scientists think that some of the environmental degradation caused after agriculture was introduced into the area was being reversed, and the health of the river and estuary has improved enough for the fish to make a comeback.