236 Transactions. — Zoology. 



be done. I had a tank erected, 12ft. long by 30iu, wide and 

 24in. deep, divided into three compartments with movable 

 partitions. The front of this tank or aquarium is of glass, so 

 that I can observe all the movements of the fish ; and, although 

 I have not a constant flow of water, there is sufficient to 

 answer my purpose. I observed that in all the streams in 

 this district there are large numbers of minnows (Galaxias 

 attenuatus), which are pretty to look at, and apparently inno- 

 cent and timid ; but, as they take the worm freely, I thought 

 they might just as readily take the young trout. I placed 

 seven of them in the tank, and gave them worms nearly as 

 long as themselves. These they ate greedily. I then gave 

 them dead whit.ebait, which they ate as freely. My next 

 experiment was with twenty-five live trout six weeks old ; and 

 wuthin twelve hours they had all disappeared except one, 

 which may have been hidden among the plants, and so escaped 

 their observation. By this time I was satisfied that they were 

 at least one cause of the mischief, but to make certain I tried 

 once more. I placed two minnows in the tank with fifteen 

 trout nine weeks old ; and within half an hour three of the 

 latter had disappeared. I then dissected one of the minnows, 

 and took from it one of the trout, which had been swallowed 

 whole. I may add that the minnows had been well fed before 

 they were placed with the trout ; and if they will devour them 

 under these circumstances, we may well understand how 

 readily they will attack them in the streams. There may be 

 other reasons for our want of success in stocking the streams ; 

 but, apart from all others, this of itself is sufficient to account 

 for it. 



Experience has proved that it will not do to place the 

 young fry in the streams and leave them to take care of them- 

 selves, and an important question would be, at what age will 

 they be old enough and strong enough. This I cannot answer 

 definitely. I have had the trout with the minnows when they 

 (the trout) were seven months old, and they seemed to live 

 in harmony. Whether they would do so at an earlier stage I 

 cannot say. 



. I think if the following plan were adopted we might rea- 

 sonably look for success : Let the fry be brought from the 

 breeding-ponds, as formerly, when they are, say, four or five 

 weeks old, before they have lost the umbilical sac, for reasons 

 which will be apparent to any one at all acquainted with the 

 subject. Place them in a pond through which there is a con- 

 stant flow of water, and where other fish cannot get at them. 

 Let them be kept there until they are, say, twelve months old, 

 after which it will be quite safe to turn them into the stream. 

 The pond could be cut out close to the stream from which the 

 water-supply would be taken, and the overflow could go back 



