210 How to obtain it. 



piecemeal, as they are quite helpless when once an oar is disabled. 

 Older fry hunt them alone, and seem to esteem them a great 

 delicacy. They take short nights over the water in bright weather, 

 from April to July, during the breeding season, and will leave 

 their quarters during a drought, and fly to other waters at any 

 time that they may be compelled to do so. 



They are very prolific, laying a number of small round whitish 

 eggs, which in size and appearance somewhat resemble those of 

 the mackerel. They may be found in numbers on the undersides 

 of the floating leaves of aquatic plants, and also on pieces of wood, 

 and on dead leaves in the water. On the whole it is an insect 

 that may be looked upon with some favour, although it may kill 

 off a few of the more weakly, or it may be sickly fry, when it gets 

 a chance. It is useful as a scavenger, and as soon as the fry have 

 grown a little they will not leave a corixa alive within their 

 borders. 



When the fry have advanced so far, that they can thoroughly 

 master a corixa, they turn their attention to, and are large enough 

 to take, a fresh water shrimp (Gammarus pulex), which is 

 a crustacean of the sub-class Edriophalina. 

 This is one of our very best friends, which should 

 be introduced by all means into all trout waters, 

 and cultivated assiduously. It may easily 

 be distinguished by anyone, and in general 

 appearance closely resembles the sand hoppers, 

 so common on the sea-shore. It is a very (Ga ,,^ 7 ^ ) 

 prolific breeder, and retains its eggs until they 

 are hatched. It is an excellent scavenger, and appears to be 

 harmless, although slander says it likes fish eggs. It does not 

 appear to do any harm to trout ova, for the experiment has now 

 been repeatedly tried, by placing gammari in the same tank with 

 trout eggs. Although their movements have been carefully 

 watched, they have not been detected doing any harm. They 

 may hide under them if they get the chance, but, seeing that in 

 natural waters trout eggs are buried in the gravel, such an 

 occurrence is not likely to take place. In the hatching boxes, of 

 course, they can do no harm, even if so disposed, for the simple 

 reason that they are not allowed to enter. It is their nature to 



