How to obtain tt. IOI 
likely again to be eradicated. Some kinds do much better than 
others, and among these perhaps one of the best is the Zimnea 
peregra. 
Crustaceans in the shape of fresh water shrimps (Gammarus 
pulex) are also very easily introduced, and should be put into the 
stream flowing into the pond, where they will at first be more at 
home, and they or their progeny will soon drop down into the 
pond and stock it. The fact must not be overlooked that some 
crustaceans are parasitic on fish. Some knowledge is, therefore, 
requisite before introducing living creatures into a trout pond, or 
a serious mistake may possibly be made. I once had a 
consignment of fish from abroad, and on arrival they were closely 
examined before being turned out, and were found to be infested 
by a leech. These creatures caused the fish much annoyance, if 
they were not otherwise hurtful. Each fish was carefully 
examined and the pests removed, and after being passed twice 
through salt baths, and performing quarantine, they were found to 
be quite clean, and were then turned out. Seven of these leeches 
were put into a glass jar for further examination, and a couple of 
sticklebacks were introduced. A leech immediately stuck to one 
of them, having hold of the jar at the same time, and in spite of 
the utmost endeavours of the fish, the leech held it for fifteen 
seconds or more, and then relinquished its hold of the glass and 
stuck to the fish with both extremities, to its evident great 
annoyance. The others soon followed suit and took hold also. 
Next day, however, the tables were turned, four of them having 
taken inside berths. The remaining three still adhered firmly to 
one fish. These leeches when examined under the microscope 
were found to be infested by scores of smaller parasites. 
“Great fleas have little fleas 
To live upon and bite ‘em; 
Little fleas have lesser fleas 
And so ad infinitum.” 
This occurrence suggests the exercise of great care in 
importing foreign fish lest we import foreign parasites and plagues, 
as so frequently in the past. All imported fish should be 
carefully examined, dipped, and quarantined, before being passed 
into British waters. 
