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 effect 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, 
which 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, while 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 Fish become perfectly black ; so that but 
