NOTES ON FISH IN CAPTIVITY. 
29 
destitute of plants. I drag my net along the sides of the 
Loch only to find a few specimens of L . pevegver. I try again 
and again with a like result. It is useless wasting time here, 
so I determine to cross the hills and get on to the Little 
Fleet where I hope to bag some specimen of Unio mavgavitifev, 
and perhaps be rewarded with a pearl for my trouble. 
H. Mackay. 
(To be continued.) 
notes on fish in captivity. 
The undermentioned observations are made upon fish kept 
by me in a large glass-sided tank, inhabited by a jack and 
some perch, dace, roach, barbel and sticklebacks. 
First and foremost comes the jack. It has now been with me 
nearly two years, during which time it has consumed a large 
quantity of food, for its voracity is really remarkable. In 
length it is about eighteen inches, and appears to have grown 
about three inches during its captivity. Its food consists of 
frogs, small fish and an occasional gold-fish by way of a luxury. 
Gold-fish are its favourite food, and as soon as one is placed 
in the tank the jack leaps through the water at it with great 
eagerness and devours it. 
A number of sticklebacks have been introduced from time 
to time, and although they do not seem to be a favourite dish 
with the jack, yet when pressed by hunger he will clear them 
out one by one, but only slowly. The jack on several 
occasions had been struck on the head when rushing after 
these little fish by coming in contact with the sides of the 
tank. After a time he seemed to wish to avert this, as he 
would only pounce upon them when in the middle of the 
tank, and the little fish on their part seemed to know his pur¬ 
pose, for they would keep in small bands quite close to the 
sides, and woe to any straggler that strayed to the centre. 
Yellow coloured frogs the jack likes best, and refuses to 
look at the darker coloured ones, although perhaps hungry. 
At various times, perch, dace and roach are introduced. The 
dace and roach, on seeing the jack, go scuttling along as if 
wanting to hide from their enemy, but not so with the perch ; 
they go sailing by the pike with their spinous backs raised 
up as much as to say, “ We are protected by these prickly 
spines; you will not attack us, you know our spines will prick 
you.” This jack however will make a meal of the perch, but 
not until after he has consumed all the other fish and is down¬ 
right hungry; then he will seize on the perch, spines and all. 
