FRESHWATER FISPI EPIDEMICS IN QUEENSI-AXD RIVERS. 183 



3^ear prior to the outbreak. Fish died chiefly in die large 

 waterholes. The water was des<?ribed as good ; though not 

 clear it was not muddy, and as far as Mr. Rudd knew it con- 

 tained very little mineral matter. No bore-water entered he 

 holes where the epidemic occurred, and weeds were not obvious. 

 He mentioned that some local people thought that overstocking 

 was the cause, but stated that bird life was as plentiful as 

 during the period when ihe epidemic was not prevalent. The 

 aboriginals informed him that they had never known fish to 

 die in such quantities before and believed that the cold weather 

 was the cause. In places blacks were employed to drag the dead 

 fish out of the waterholes with wire-netting, the water having 

 become too polluted to be used for drinking. Sick fish were 

 eaten by thf' blacks without apparent ill effect. 



Mr. A. V. Stretton, who is in charge of the police station at 

 Rankine River, wrote on 31st July 1920 regarding the outbreaks 

 at Anthony's Lagoon (Northern Territory) where he was 

 previously stationed. From his replies to questions submitted 

 to him, the following information has been taken. The fish 

 affected were chiefly perch {PlectropUtes), only a few catfish 

 being among them. They could be readily caught by hand 

 when near the water's edge. All were very fat. A noticeable 

 feature in regard to affected catfish Avas the presence of a led 

 streak along the abdomen. Though the fish were slightly 

 swollen, the bluish colour referred to by some of the previously 

 reported observers was not noticed. He stated that the}^ began 

 to die at the lagoon on 10th August 1917, destruction pro- 

 ceeding for eleven days, the fish dying in " countless thousands." 

 On 20th March 1918 the epidemic reaj)peared in spite of the 

 fact that the river was running, and continued until 12th 

 April, a period of about 23 days. There was another out- 

 break on 16th July 1918, lasting nine daj^s. There had not been 

 any further occurrence up to the time that Mr. Stretton had left 

 the locality. 



The epidemic appeared and disajipeared suddenly, and in 

 his opinion had no relation to drought. Though no rain fell 

 during the periods when the mortality was in evidence, yet 

 there had been abundant rainfall in 1917 and 1918 — viz., 32 and 

 30 inches respectively, whereas the annual average was only 

 18 inches. There was no relation to abnormally cold weather, 

 as the temperatures during the winter were not noticeably 

 lower than during other years. The water was not charged 



