diff --git a/django/db/backends/oracle/introspection.py b/django/db/backends/oracle/introspection.py
index 1250a02f1d..056edb6ce6 100644
--- a/django/db/backends/oracle/introspection.py
+++ b/django/db/backends/oracle/introspection.py
@@ -16,22 +16,15 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
         cx_Oracle.CLOB: 'TextField',
         cx_Oracle.DATETIME: 'DateField',
         cx_Oracle.FIXED_CHAR: 'CharField',
+        cx_Oracle.FIXED_NCHAR: 'CharField',
+        cx_Oracle.NATIVE_FLOAT: 'FloatField',
+        cx_Oracle.NCHAR: 'CharField',
         cx_Oracle.NCLOB: 'TextField',
         cx_Oracle.NUMBER: 'DecimalField',
         cx_Oracle.STRING: 'CharField',
         cx_Oracle.TIMESTAMP: 'DateTimeField',
     }
 
-    try:
-        data_types_reverse[cx_Oracle.NATIVE_FLOAT] = 'FloatField'
-    except AttributeError:
-        pass
-
-    try:
-        data_types_reverse[cx_Oracle.UNICODE] = 'CharField'
-    except AttributeError:
-        pass
-
     cache_bust_counter = 1
 
     def get_field_type(self, data_type, description):