244 How to obtain it. 



Sometimes, instead of appearing emaciated, the fish which 

 ,look quite healthy and well will suddenly commence drifting on 

 to the screen in large numbers. This is probably because their 

 food has disagreed with them, and feeling sickly they are carried 

 down by the stream, and will die if not removed. The best way 

 of dealing with such fish is to place them, like their " lanky " 

 brethren, in a suitable raceway, where many of them will recover. 

 A raceway used for this purpose should terminate, if possible, in 

 a pond, in which the fish can remain, and which should contain a 

 good supply of natural food. They will remain long enough in 

 the raceway to receive much benefit, and on reaching the pond 

 will be stronger, and the change of diet will soon put them right 

 again. 



Many are the diseases to which trout are liable. A very 

 sudden change of temperature will cause them to suffer from in- 

 flammation of the gills, which is sometimes fatal ; often they get 

 over an attack of this disorder with the result, some people think, 

 of deficient gill covers. This may be a consequence, but I rather 

 think that fungus is much more to blame for it. The fungus is 

 apt to grow on the edge of the gill covers, and although it may be 

 afterwards cured, yet it interferes with the development of the 

 opercula, which become permanently contracted in consequence. 

 Young trout sometimes suffer from parasites, and when such is 

 found to be the case a salt bath is beneficial, and will usually put 

 matters right, though sometimes several applications are necessary 

 before the desired end is obtained. I have occasionally seen 

 several cases of blindness amongst a lot of trout. It attacks the 

 best and finest fish in the pond, and they become very light in 

 colour. The strangest part of the malady is that they do not, at 

 least for a while, fall off in condition. They are easily picked out 

 at a glance from amongst the other fish, and are not worth keep- 

 ing. When old fish become blind it has the effect of making them 

 dark in colour and inferior in condition. Probably this is because 

 they do not so readily adapt themselves to circumstances as younger 

 fish do. I have seen the latter feeding freely, and evidently guided 

 to their food by the senses of touch and smell, and they get very 

 expert at finding food without taking much exercise. This accounts 

 for their keeping so long in good condition. 



