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Upon receiving, loosen cap and aerate culture with a clean pipet. Hydra
should be kept in dim light at a temperature of 21 °C. Too much light will
permit algal growth, which is detrimental to the hydras. Culture Hydra in
a small aquarium or a large culture dish containing filtered spring or pond
water. Do not use tap or deionized water.

Hydra are extremely difficult to culture for a long period of time. They feed on live food, usually Daphnia or brine shrimp. Feed Hydra once a day. Allow several
animals for each Hydra as the culture grows. Uneaten food must be removed
each day or it will foul the water. The easiest way is to decant off the
majority of the water and replace it with fresh spring or pond water. Even well
maintained hydra cultures go through a period of depression caused by incorrect
temperature, insufficient oxygen, overfeeding or fouled water. If hydras start
to die off, immediately transfer all organisms to clean, fresh water.

When culturing green hydras (Chlorohydra viridissima) allow for 8
to 10 hours of light per day. This organism has within its tissues symbiotic
green algae which require light for photosynthesis.

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