242 How to obtain it. 



many fish is considerable, and is a thing that is not often taken 

 into account by practical men. It is a matter that is of vital im- 

 portance, however, as the fish, although they may live, will be 

 liable to be killed by circumstances which would not otherwise 

 affect them. The slackening of the water supply accidental or 

 otherwise a rush of surface water after heavy rain, or even a 

 freshet, may kill a lot of them, and often the best fish are those 

 jthat suffer under such circumstances. Do not overcrowd the fish 

 ; therefore. 



A pond sixty feet long, four feet wide, and about three feet 



k^ flr 1! ^ ee P' w ^ kold ten or fifteen thousand fry at first, and give them ( r 



plenty of room to grow, but by the end of July the number should N ' \ ^ 

 . it be reduced to five thousand, which may be left till October, 

 when they should again be thinned out, or better still, put into 



i , *| | | larger ponds. When pressed for pond room I have put as many 

 as thirty thousand fry into a nursery pond of the size just mentioned, 

 but they soon required thinning out, and whilst they were in the 

 pond had a good current of water running over them. It is most 

 important that the water supply should be at all times ample. 

 There should be more than is actually required, so that at any 

 ' time an extra quantity can be turned on. The amount of water 

 run through each set of nursery ponds should depend a good deal 

 on surrounding circumstances, but from fifty to a hundred gallons 

 per minute is a fair quantity, and this will keep seven ponds 

 y ^ going, other things being equal. If more ponds be required, then 

 an entirely additional supply of water will be needed. At the 

 Solway Fishery there are several sets of nursery ponds, and the 

 water from each set is conducted into a raceway, and after flowing 

 with a good ripple for a quarter of a mile is again used for supply- 

 ing ponds containing larger fish. 



A given supply of water will only support a limited number 

 of fish, and after being passed through a series of ponds it requires 

 purification. There is no better plan than allowing it to ripple 

 over the stones, and to pass through a pond or even a raceway 

 containing vegetation. 



/ In this way oxygen is absorbed from the air, and is also 



received from the plants, which, on the other hand, take up the 

 deleterious matter with which the water has become more or less 



' 



