What water temperature should it live in?

[veneficus]

Lissotriton vulgaris What water temperature should it live in?

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[Plomeo_Andrew]

Lissotriton vulgaris What water temperature should it live in?

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Juveniles or adults?

 

[veneficus]

Juveniles or adults?

juveniles

 

[Plomeo_Andrew]

juveniles

My friends and I kept the juveniles in a temperature range from 20~28 degrees Celsius. They went well.

The highest tolerated temperature is 30 degrees Celsius, but only for a short period of time.

 

[JM29]

Lissotriton vulgaris is a widespread european species, which inhabits a lot a different environments.
The relevant answer depends on the origin of your strain.