54 FISH CULTURE. 



impure from heavy floods. These floods even swelled 

 the Thames, so that it inundated the meadows and 



i 



covered the boxes six or eight inches in depth ; and 

 as at that period the young Rhine salmon had just 

 commenced feeding, and they could not be got at for 

 some days, a great many died, and many more escaped 

 from the boxes. Fortunately, the trout were un- 

 injured ; and the greater part of the stock were, in 

 due time, safely consigned to the Thames. 



Trout ova are generally supposed to occupy about 

 the same period as salmon. I think, however, it may 

 be shortened somewhat. In the same water as noted 

 above, as I have said, we found the hatching range 

 from fifty to sixty days, while in the boxes placed 

 in the meadows, where the water is several degrees 

 warmer, trout ova hatched in forty-eight days, the 

 eyes being visible at thirty-five days, instead of from 

 forty to forty-five ; and no doubt even this period may 

 be greatly abridged. 1 So that it will be seen, in this 

 instance alone, temperature could make a difference 



1 Mr. Fiy, in his translation of the proceedings of the French 

 pisciculturists, states that salmon and trout ova in high tempera- 

 tures are sometimes hatched even in thirty days. I have never seen 

 any hatched in so short a period, and certainly should prefer a more 

 moderate temperature. He states also that pike's eggs have been 

 hatched in nine days, the usual time being about three weeks. 

 Charr in from twelve to fifteen days, the usual time being here also 

 three weeks. 



