THE MARINE AQUAKIUM. 147 



a minnow more food than he will swallow — and even when 

 he can put no more into his stomach, he will fill his mouth 

 and retire to some secluded spot to sleep off his meal. 



There is one thing that is very likely to happen to a 

 tyro when stocking his tank, and which he will find to be 

 ruination to the well-being of an Aquarium; and that is, 

 overstocking. This is more likely to happen to a marine 

 collection than a fresh-water one, as we are apt to place 

 everything that we pick up on the shore in our tank, 

 and so, at last, we go beyond the limit that nature has 

 assigned for the proper balance of animal and vegetable 

 life in the ocean, river and pond. When this happens, we 

 observe our most tender animals show signs of uneasiness, 

 and, at last die ; the hermit crabs, being those that 

 soonest sicken and die, and if not removed, their bodies 

 soon foul the water and cause the death of the other 

 creatures in the tank. All the other inhabitants of our 

 Aquarium may appear in a healthy and flourishing condition, 

 except the poor hermits, and when they crawl out of their 

 shells, braving the minnows and other fish, we may be sure 

 then, there is something wrong, and that the collection 

 requires attending to. In such a case, it is best to see if 

 the tank be overstocked, and it is surely so, "if it contain 

 more inhabitants in proportion to its size than the one 

 I have spoken of in chapter two. Then we must remove 

 some of the fish and other creatures. If this does not 

 remedy the evil, and things still wear an unpleasant look, 

 it is best to remove and chauge the water ; and, indeed, 

 sometimes to begin with a new stock of sea-weeds. 



The molluscs in the marine collection do not seem to 



