An aquarium heater can be accommodated with the aid of the Reef One heater tropical. The aquarium can then house small tropical fish. A snap out section in the biOrb light unit provides a gap into which the lead from the heater can rest, keeping the lead tidy whilst allowing the light unit to remain snugly fitted in the top. The Heater Pack contains a 50 watt hater, glass thermometer, sample of tropical fish food and heater stand. Heater stand enables the fixing of a heater the curved inside of the biOrb. Although designed for use in the biOrb, the heater stand can be used in most aquariums if desired.