He maintained an aquarium and made Sunday-morning expeditions to the ravines at the back of Malabar Hill to search for mosquito larvae to feed its inmates. Mr. Aitken investigated the capabilities for the destruction of larvae, of a small surface-feeding fish with an ivory-white spot on the top of its head, which he had found at Vihar in the stream below the bund. It took him some time to identify these particular fishes ("Haplochilus lineatus") which he called "Scooties" for their lightning rapidity of their movements. With these he stocked the ornamental fountains of Bombay to keep them from becoming breeding-grounds for mosquitoes, and they are now largely used throughout India for this very purpose.