38 Part III. — Twenty-eighth Annual Report 



V.— BACTERIOLOGICAL INVESTIGATION AS TO THE CAUSE 

 OF AX OUTBREAK OF DISEASE AMONGST THE FISH 

 AT THE MARINE LABORATORY, BAY OF XIGG, ABER- 

 DEEN. By A . G. Anderson. M.D., D.Sc, D.PH., M.A. 



About the end of August 1908, some haddocks and whitings were 

 required for replenishing the tanks at the Marine Laboratory at the Bay of 

 Xigg, Aberdeen, where for the previous eighteen months I had been carrying 

 out some experimental work on the decomposition of fish and its detection 

 from the public health point of view. This work has been already published 

 by the Fishery Board for Scotland in their Twenty-sixth Annual Report 

 (Part III.) — Scientific fncestigations. 



On the evening of the 21st August some were caught about a quarter 

 mile from the shore in six fathoms of water and about 200 yards from the 

 mouth of the a sewer. The fish were conveyed to the Laboratory 

 in two large galvanized tin boxes and placed in two of the tanks at the 

 Marine Station, amongst other haddocks and whitings which had been 

 in the same tanks for about nine months, and which had been caught three 

 to four miles from the shore. The attendant officer at the Laboratory, who 

 was in charge of the operations in catching and conveying the fish to the 

 tanks, states that he distinctly observed a few spots on some of the fish 

 which attracted his attention. Some of the spots were small and pale in 

 colour, about the size of a threepenny piece ; others were larger, reddish- 

 looking, and about the size of a crown piece. These appearances he observed 

 in four or five of the fishes. During the second night after being placed in 

 the tanks, one of the haddocks died ; and the disease was observed to be 

 spreading. In the case of those previously showing small affected areas, the 

 areas were now seen to be getting larger and redder ; while the rest of the fish 

 not already affected, and including those recently caught and those previously 

 in the tank, now began to show small spots in the initial stage, which were 

 paling and desquamating. The spots were not limited to any particular 

 area, although most common on the neck, back, and tail. By the third 

 day many of the fish showed sluggish movements and a few more died. 

 By the fifth day all the fish in these tanks were dead. The number of 

 haddocks and of whitings in separate tanks previous to introduction of 

 those caught on 21st August is given as probably 25 of each, and those 

 introduced about one dozen each. 



Appearance of the Ulcers, 



On examination of the fish after death the ulcers were seen not to be 

 localised to any one part of the body, but irregularly distributed on the neck, 

 back, tail, and on the fins. They varied in size from one to four or five 

 millimetres in diameter, and were of the spreading and sloughing type. 

 The base of the ulcer was depressed, often reaching down to the muscular 

 tissue in the more advanced ulcers, and usually showing some necrosed and 

 sloughing tissue with some grumous pus. The edges were inflamed, 

 irregular and ragged, and very much undermined. The surrouuding tissues 

 in the more advanced ulcers were soft and ©edematous. In five of the fish 

 examined the base presented a slightly injected appearance, with apparently 

 some attempt at reaction on the part of the tissues against the attacking 

 micro-organisms ; but in no case did the ulcer appear to be passing into the 

 condition of healing with the formation of true granulation tissue. In many 



