FRY IN REARING PONDS— THEIR ENEMIES. 45 



tray and balance tliemselves in the water, with, their heads directed up stream, 

 and are ready to seize any suitable passing object. Now it is absolutely 

 necessary that they should be fed,* commencing with one meal a day, and 

 being careful that no remains of food shall be left to corrupt at the bottom 

 of the tray. Some believe that at this period there is more danger of over- 

 than of under-feeding, while others warn the inexperienced against the fry being 

 too crowded, as such is very productive of disease. Care has likewise to be 

 taken against their dividing themselves into two sets, and the stronger taking 

 forcible possession of the best places, where food is most plentiful, and driving 

 the weaker ones away to herd by themselves, generally to the lower end of the 

 tray, and here some may be found lying dead against the screen. f Should they 

 subsequently become languid, cease feeding, avoid the current, and commence to 

 die in numbers, such is possibly due to decomposition of uneaten food in the trays, 

 or because the diet is unsuitable ; and for the first Livingston-Stone advises as a 

 remedy the free application of common earth, covering the bottom of the tray to 

 half-an-inch or more. "What has already been enumerated as suitable food may 

 be given, also microscopic forms of animal life — as the larvse of gnats, Daphnia, 

 Cyclops, &c., which may be skimmed from the surfaces of ditches or obtained 

 from stagnant pieces of water. 



After a varying period, the fry, if kept in the trays, will commence springing 

 out of the water, evidently desirous of changing their abode, and they can be 

 turned into larger rearing boxes, or transferred to suitable ponds where there is a 

 constant supply of the purest water and they are protected fi-om their enemies. 

 If crowded in this stage they are subsequently usually stunted. These rearing 

 ponds, or boxes, should afford shade to the fry. 



When turned into rearing ponds fed by a stream of water, weeds or other forms 

 of shade should be present, while such as contain the natural food as Daphnia, 

 Cydops, fresh-water snails or Idmnma, or fresh-water shrimps or Gammarus pulex, 

 are best adapted for their thriving in. But the locality may be too cold or too far 

 north for sufficient nourishment to be present, and then artificial feedingj must 

 be continued. 



The period required in order to prepare young trout for travelling varies from 

 three or four days in the case of yearlings to as many weeks for larger examples. 

 While for stocking purposes yearlings§ are better than those which are younger, 

 because they can find their own food which younger ones are often unable to 

 accomplish. No difficulty is now experienced in conveying these fish alive for a 

 distance which does not take more than twenty -four hours if the water is iced, but 

 unless the water into which they are going to be transferred is of a similar 

 temperature some loss will probably arise from gill-fever, and cold weather is most 

 suited for their conveyance. Aeration of the water may be assisted by the forms 

 in which some of the transporting cans are now made, or by the use of an aerating 

 pump or other suitable contrivance. 



Some of the enemies or vermin which attack the fry have already been referred 

 to as inimical to the eggs (see p. 28), for these little fish are esteemed as delicate 

 morsels by rats and mice, also by birds, as swans, geese, ducks, moor-hens, water- 

 ouzels, and kingfishers, while as they get larger, sea-gulls and terns join in the 



* A simple and very effective feeder is employed at Howietoun, consisting of a long wooden 

 handle, at the end of which is fixed at right angles the feeder which resembles a tumbler made of 

 perforated zinc, into this the food is placed, and as it is agitated in the water it gradually 

 escapes. 



t Livingston-Stone observed that " there is no need wliat&ver of this. If they get against the 

 screens it is because they are weak, and you may know that their weakness has come either from 

 their being too much crowded, too little fed, or from being actually sick " (page 174). 



J Irrespective of the forms of food alluded to, Kufier has suggested for gi'owing fish, meat or 

 fish being boiled, ground up and mixed in the proportion of three parts of it to one part of flour. 

 Haack proposed horse-flesh even if salted, chopped with a meat cutter, for forms up to one-year- 

 old, and cut into cubes for larger : sheep's liver ground through a fine sieve and mixed with water : 

 sheep's or calves' brains passed through a wire sieve : dried ants' eggs likewise ground fine : or 

 sheep's lungs boiled in salt water. The ova of other forms of fish has also been used : English 

 dog-biscuits, worms and maggots. 



§ When coarse or large fish are present in the water it is intended to stock, two-year-old 

 fish are found to succeed best. 



