220 The Fishes of the Lower Wharfe Basin. 
ventral, anal, and caudal appendages are generally tinged with 
deep vermilion, and the characteristic colour varies from 
bluish olive, to brassy yellow in mature and well grown speci- 
mens. The Wharfe should be an _ idealriver for these fish, 
but unfortunately the species appears to be limited to the 
lower reaches entirely. I have taken specimens at Tadcaster, 
but above this point where the dilution of deleterious matter 
becomes lessened, it is only to be met with in ponds, etc., near 
the river side.* This seems to indicate, that at one time, 
probably before we had to contend with sewage contamination ; 
it was plentiful as far up as Otley. In the early part of 1912 
a pond near Ben Rhydding containing a large quantity of 
small Perch was emptied, and the fish eventually found their 
way into the river.t 
The fecundity of the Perch is extraordinary, more especially 
in semi-stagnant waters, though in this country it seldom 
attains to a weight of more than three pounds. It is a voracious 
fish, particularly when small and predatory in its habits. 
Its food consists of gudgeon, minnows, and other small fry, 
besides worms, crustaceans, etc. It is readily taken on the 
rod, and, being gregarious, it is often caught in large numbers. 
When the Perch is well grown its flesh is held in high esteem. 
The species spawns from the middle of March to the middle 
of April and soon afterwards regains its strength and condition. 
Though a hardy fish and easily transported from one locality 
to another (in the winter months requiring only a covering of 
damp moss in place of its natural element) it is nevertheless 
extremely susceptible to foreign or poisonous substances 
which may find their way into the water, and from this cause 
very often succumbs. 
The large Perch of Malham Tarn in Craven are famous. 
Huxley described them as exceedingly black, and generally 
found to be blind. By some authorities this is stated to be 
due to a parasitic disease to which the fish is addicted. In 
enclosed waters the Perch does not appear to thrive in com- 
pany with the Roach. 
THE RUFFE OR Pope closely resembles the Perch in 
form, but seldom grows to a greater length than four or six 
inches. 
The colour is yellow to olive. It can be caught on the rod 
all the year round, and like the Perch, prefers a quiet swim 
with a gravel bottom, to the strong streams. From the 
* Some very good specimens are taken in the river above this point, 
especially in the neighbourhood of Harewood.—Ep. 
+ These particular Perch were not indigenous to the locality, but 
were introduced by an angler several years ago from the Aire valley 
the parent stock consisting of about forty or fifty specimens. 
+ This is hardly so at the present day.—ED. 
Natur alist, 
