ILLUSTRATIONS 



1 Sectional view of a general-purpose aquarium 



building 16 



2 Sand filter for removal of silt and other fine mat- 



ter 21 



S Screen filter for removal of fishes and other larger 



biotic pollutants 22 



4 A suction drain which permits cleaning bottom of 



tanks 24 



5 Arrangement of overflow to secure proper circu- 



lation of water 25 



6 Agitator for aerating aquaria and hauling tanks 62 



7 The air-lift pump is of value in filtering water of 



small individual tanks 63 



8 Hauling tank designed for a pick-up truck 79 



