In the sea aquarium, Malayan Angels (or Diamond fishes or Moonfishes)
should be kept in small groups of three of more because on the reef they occur in dense
shoals of up to a thousand fishes, moving with uncanny precision. They tend to be bullied
in the aquarium unless provided with adequate retreats. Their low price, readiness to
accept even the most mundane foodstuffs and strong resistance to disease makes them an
ideal choice for the beginner. Their close relative from the West African seaboard,
Monodactylus sebae, are more attractive but not quite so hardy in captivity.
Since these three species of fishes are occasionally sold by dealers from brackish and
even freshwater tanks, the specific gravity of the water in which they are bought should
be carefully checked. If the specific gravity differs greatly from that in the marine
aquarists tank, this imbalance should be slowly corrected by gradually adding tank
water to polythene bag in which the fishes were carried home.