20 



AQUARIUM MANAGEMENT 



sionally see whether the mussels are living, as they decompose very 

 rapidly and spoil the aquarium water. This can be done by tapping 

 lightly on the shell and seeing whether they respond by closing. It is 

 doubtful whether the benefits arising from their use are equal to the risks 

 incurred in their dying, especially in tropical aquaria. They may be 

 gathered by raking the mud and sand of freshwater bodies. Their presence 

 is usually indicated by some half-shells lying around in the water. 



Fig. 10. Freshwater Mussel, Showing Water Intake and Outlet; Also "Foot" 



With Which It Burrows and Travels 



Weatherfish. A curious and useful scavenger is an eel-like fish 

 called the Weatherfish. Varieties are native to Europe and Asia. They 

 are freely imported and inexpensive. When not scouring the aquarium 

 bottom for bits of decomposing matter, they sometimes burrow into the 



Fig. 11. The Weatherfish (Misgurnus fossilis) 



sand, leaving only the head exposed, producing a quaint appearance. In 

 their special occupation as scavengers they employ a method which is 

 both effectual and interesting. The dirt and top sand are taken in the 

 mouth and rapidly shot out through the gills. Any particle of food con- 

 sidered edible is automatically separated from the bulk of the dirt and 

 swallowed. 



Goldfish keep the sand loose and in good condition by picking it up 

 in their mouths, but most other aquarium fishes do not touch it, which 

 allows it to cake. The Weatherfish can be introduced with such fishes, 

 even a single small one keeping the sand in a large aquarium loose on the 

 top. Sizes of four inches or less are best. They are all apt to agitate 

 the sediment, especially the larger ones. 



