Discoveries of creatures like Dippy should always be reported to the government through organisations such as the National Centre for Reptile Welfare.
Director Chris Newman said there were no recorded sightings of Mexican axolotls in the world or the UK, adding that Evie probably saved its life.
“This is a quite a unique situation, and I think the young female has a keen eye to actually spot it.
I think she did remarkable to find him,” he added.
Without her help, Newman said the axolotl had little chance of living very long, so she “did him a real favour” by catching him.
“That itself is no mean feat,” he said.
“They’re quite slippery, so I think she did really well.”