A problem with conventional rearing apparatuses for deep-sea organisms was difficulty in supplying dissolved gas into water in an appropriate amount.A dissolved gas supplying device 1 for supplying dissolved gas such as hydrogen sulfide, methane and hydrogen to water in a water tank, includes: a circulation path 11 to take out the water from the water tank A and return it to the water tank a pressure pump 12 to allow the water to flow through the circulation path 11 a gas cylinder 13 filled with gas to be dissolved a dissolved gas supplying means 14 that is disposed in the circulation path 11 to allow the water to pass through it and to dissolve the gas of the gas cylinder 13 in the water and a gas regulating valve 16 to open/close a gas channel 15 that connects the gas cylinder 13 to the dissolved gas supplying means 14. With this configuration, the device can supply the dissolved gas into the water in an appropriate amount according to need. Therefore, the device is very suitable for rearing apparatuses for aquatic organisms of chemosynthetic ecosystems that utilize the dissolved gas.
