We have blue tailed skinks now after we put in the koi pond.
This a juvenile and the blue tail goes away as they mature and get bigger.
The spider population plummeted around our house once the skinks showed up. We have lots of toads as well.
The lay a zillion eggs, the koi eat all they can, and then eat the tadpoles. A few dozen baby toads emerge, and if they get too thick we gather some and take them to a local creek and sing born free.