As nouns the difference between aquarium and tankmate
is that aquarium is a tank, often made of glass, for keeping live fish or other aquatic animals while tankmate is an aquarium fish that shares the same tank as another.
aquarium
Noun
(en-noun)
A tank, often made of glass, for keeping live fish or other aquatic animals.
A public place where live fish and other aquatic animals are exhibited.
tankmate
English
Noun
(
en noun)
An aquarium fish that shares the same tank as another