460 SALMON AND TROUT. 
cases to improve it), and if a number of ponds are constructed 
on different levels, these will preserve the food, it the volume of 
water passing through is sufficient, and yet at all times under - 
perfect control. The raising of trout appears to be entirely a 
question of food, both in quality, size, and quantity; and unless 
this can be provided naturally, the rearing of any great number 
of fish is a most expensive undertaking, various kinds of meat or 
offal having to be procured, and a staff of assistants constantly 
employed in chopping or otherwise preparing the food. The 
system of feeding at the Howietown Fishery is almost wholly 
artificial, especially for the large fish, and this establishment 
(by far the largest in the world) turns out great numbers of 
yearling fish. There is but little natural food to be found in 
the water, but this has lately been introduced, and watercress 
cultivated in all the ponds. A pisciculturist, however, relying 
entirely on natural food must have larger ponds and more of 
them, involving a considerable original outlay. Without proper 
food, natural or artificial, the loss would be something difficult 
to realise—perhaps equal to that arising in the natural state, 
where it is thought to be probably not less than 999 per 1000! 
If a small proportion of the young fry—turned direct into 
the ponds from the hatchery—die, they are devoured by fresh- 
water shrimps and other carnivorous insects, valuable in them- 
selves as fishes’ food, and also acting as Nature’s scavengers 
of the water; but if proof is required that these do very little 
damage to healthy fry, the writer may mention that he has 
frequently found 80 and 85 per cent. of yearlings, which were 
placed in the ponds eleven months before as fry. Let anyone 
observe, however, the rapidity with which a dozen shrimps will 
demolish a dead ‘fry.’ They will cluster all round it, and ina 
very few moments there will be nothing left but his little back- 
bone—the fish get the best of it in the long run though ! 
Seth Green, a well known American pisciculturist, says 
‘Starvation’ is almost the only cause of mortality among fry 
yrovided they have been properly treated in the earlier stages. 
How many millions of fish have been deliberately (in some 
