THE FISHES OF THE RIVER HULL. II 
(Salmo levenensis), Grayling (Z) hymallus vulgaris), Burbot (Lota 
gulgaris), Sharp-nosed Eel (Anguilla vulgaris), Broad-nosed Eel 
(A. laterostris), Sea Lamprey (Petromyzon marinus), Lampern 
(P. fluviatilis), Flounder (Platessa flesus).* 
The PERCH is a very conspicuous object when in its native 
element. We generally find an animal, when it displays 
such colours, in a position to fear very little from its enemies. 
To what then does the perch owe its comparative immunity from 
danger? At first it might seem that the dorsal fin protected it, 
and it is therefore able to display its sexual colours without 
danger ; but I think it is only in a small degree attributable to 
this cause, for the pike, the perch’s greatest enemy, seizes it 
whenever it can without hesitation. I have taken as many as 
three from the stomach of one pike. Where, then, must we look 
for the source of this protection? I think in the swiftness of the 
fish. In addition to the obvious fin power of the species, I have noted 
how much swifter it is than the roach. When walking along the sides 
of a shallow beck it is easy to determine whether there are any 
perch in a shoal of fish swimming before you, and which are 
disturbed by your presence. The perch swim along with great 
rapidity, and the roach will then make strenuous efforts to keep 
up with them. But if no perch are present, the roach do not 
swim half so quickly. In this way, in my opinion, the perch 
under ordinary circumstances may bid defiance to its enemies. 
Another fish, more gaudy perhaps for its size than the perch in 
the breeding time, is the minnow, and though this fish has not the 
vestige of a spine, or any armament whatever, it is able to repro- 
duce its kind year by year in the open river. It owes its safety 
entirely to its swiftness and activity. Before any creature can 
afford to wear a conspicuous hue in nature it has another con- 
dition to fulfil, it must be independent as regards a supply of 
food. Now the perch being strictly carnivorous, feeds on small 
fishes and crustaceans. It is important, therefore, that in order 
to catch its prey it must be sufficiently swift. To lie in ambush 
like the pike is out of the question, its conspicuous appearance 
acting like a danger signal to all the smaller members of the 
finny tribe. It must enter the lists and chase its prey. To do 
this its swiftness stands it in good stead. The perch is an imitative 
and intelligent fish. As an instance of this trait, 1 have several 
times noticed a shoal of them, which I had great difficulty in 
persuading to take a bait. Once, however, get one to invest in 
the worm or minnow, and several more are sure to be caught in 
rapid succession. One I kept in an aquarium along with some 
* The descriptions and general habits of the various fishes, being available 
in any text book on the subject, have been omitted. 
