My friend caught a strange looking animal and he's saying it is an axolotl. I keep telling him it's almost impossible, since they are almost extinct in their natural environment and he caught it in St-Larent River (Quebec, Canada)
Based on the size and location that appears to be a Common mudpuppy (Necturus maculosus). (Photo © Brian Gratwicke — CC BY)
The four toes visible on the front foot are also consistent with this identification.
Judging from the small limbs and overall size, it appears to be a large aquatic salamander, similar to Necturus maculosus, the mudpuppy. These have a pretty cosmopolitan distribution in North America, including into southern Canada. I can't tell from the photo if it has external gills.