378 
FRESH WATER STICKLEBACKS IN SEA- 
WATER AQUARIUM* 
T is perhaps undoubted that sticklebacks (Gasterosteus 
aculeatus), born and bred in fresh water, are able to 
live, apparently without inconvenience, in sea water. It 
may, however, not be uninteresting to some of our readers 
to hear a short account of an endeavour to establish fresh- 
water sticklebacks in a marine aquarium. Without fish of 
some sort, an aquarium lacks one of its greatest attractions ; 
but to keep them, it needs not only a_ well-constituted 
balance of animal and vegetable life, but also a careful 
selection of the sorts of animals. As the aquarium of which 
the following account is written is not near the sea, diffi- 
culty is found in obtaining salt water fish; and the innu- 
merable fresh-water sticklebacks in the mill-streams near 
Newport, suggested the plan of introducing some of them 
to the society of their foreign brethren. My aquarium has 
now been in existence for some fourteen months, and until 
the 29th September last without any change of water. In 
this respect, it has been more successful than any that I 
have previously had. I believe that very much depends 
on obtaining thoroughly pure water to begin with. 
During the last year, I have, on several occasions, placed 
fresh-water sticklebacks in the aquarium. Once I put in, I 
think, five, and the next morning only one was to be seen— 
and that one dead in the arms of an anemone, The same 
day I put in another seven, and afterwards five or six more, 
and similar numbers at other times, but always with the 
same result,—none survived the second day, and most of 
them disappeared after the first night. After the new sea- 
water had been placed in the aquarium, I obtained five 
sticklebacks of different sizes, one a tiny fish not more than 
half an inch long, and the other four varying from one inch 
to an inch and a half; two of these I placed at once into a 
basin of sea-water, and the other three into a basin of fresh 
water, to which I gradually added sea water. As they 
seemed to be perfectly at ease in their new element, I 
transterred them on the second day to the aquarium, and I 
then sat myself down to watch, to see if I could discover 
the enemy that destroyed these brilliant little fish. 
. Within a very few minutes one of two prawns (Palemon 
* Science Gossip. 
