Multi-chamber selective-exposure aquarium

A unitary multi-chamber selective-exposure aquarium apparatus comprising:

• a first portion forming a first aquarium chamber having an internal first transparent primary wall spanning substantially a complete width and height of the first portion;
• a second portion secured to and in fixed relative position with the first portion, the second portion forming a second aquarium chamber that is isolated from the first aquarium chamber and having an internal second transparent primary wall and having an internal second transparent primary wall spanning substantially a complete width and height of the second portion, the second transparent primary wall being positioned immediately adjacent to and substantially parallel with the first transparent primary wall, the first and second internal transparent primary walls forming a slot therebetween;
• and
• a non-transparent visual barrier device removably disposed within the slot between the first and second internal transparent primary walls for selective exposure/non-exposure of the first and second transparent primary walls which maintain the visual barrier device substantially parallel thereto,
• whereby fish in each of the first and second aquarium chambers are selectively visually exposed/non-exposed to each other's presence.