TROPICAL AQUARIUM FISHES 193 
SALVINIA 
Of the small floating aquatics Salvinia is one of the best. The heart- 
shaped leaves with bristle-like growth on the upper surface seem like 
bits of velvet connected by a thread. The roots are naturally long for 
the size of the plant but fishes usually eat them down to about half length, 
which interferes with a full development of size. In the greenhouse 
where they have a moist atmosphere and no interference they develop 
with amazing rapidity. The variety illustrated, Salvinia natans, is native 
to Europe and is the form commonly used in aquaria and pools. 
Although it is claimed that neither Salvinia nor the common wild 
Duckweed perform any oxygenating function, the author and others 
have many times seen aquaria completely covered with either of these 
plants and, with no other plants in the aquarium, the fishes were getting 
along perfectly well. 
FROGBIT 
Hydrocharis morsus-rane, requiring the same conditions as Trianea 
bogotensis, deserves more attention than it is receiving. Of very 
pretty appearance when in flower, readily obtained from dealers, there is 
os 
Fic. 147. Frocpir (Life size) 
