16 FISHES. 



which constantly ran a small and irregular supply 

 of waste water, about thirty brace of perfectly 

 healthy Trout were turned, varying from three 

 quarters of a pound to a pound each, and taken 

 from a neighbouring mill-pool. The pool into 

 which the Trout were turned, in the month of 

 August, contained a great quantity of Roach, 

 some Carp, Tench, and Perch, all healthy and 

 thriving Fish : but the Trout, when taken out 

 during the summer, and the following season, 

 seemed to have increased very little in weight. 

 With the exception of one healthy Fish of three 

 pounds, nearly all the others were found to be 

 either entirely blind or partially so, and doubt- 

 less would soon have died of starvation, as they 

 were black, thin, and poor beyond belief. Those 

 which were not too far gone to recover, I turned 

 into a neighbouring brook : but what could have 

 caused this eifect upon the Trout alone, when 

 all the other kinds of Fish, upon being taken 

 out of the same water, were healthy and in per- 

 fectly good condition, I am at a loss to imagine. 

 In the early part of the following March, I 

 caught one of these Trout of about two pounds, 

 wdiich I had the preceding summer turned into 

 the brook ; and although it was of a very good 

 colour, silvery and bright, it did not appear to 

 be well fed, though no defect in the eyes could 

 be perceived. Doubting whether to kill it or 

 turn it in again for another day, I placed it in 

 a small hoop-net, wliile I tried for another Fish, 

 and threw the net into the stream. After taking 

 two smaller Trout in very good condition, I took 

 up the net and was surprised to perceive this silvery 

 bright Fibh become perfectly black ; so that but 



