Thanks for the tips banchicawawo
there are other zones requiring changes, some of them are :
-i had to change Nektulos.eqg to Nektulos.bat (it seems there is no way to make basilisks hatchlings not appear as humans).
-North ro
-South ro
-Plane of Fire
-Blackburrow
-lavastorm
-Plane of water
I needed to replace zones files by my live client zones files to have the mobs appear with a correct skin (not as humans).