diff --git a/zoo/zoo_data/models.py b/zoo/zoo_data/models.py
index 0e02a20..cf85f58 100644
--- a/zoo/zoo_data/models.py
+++ b/zoo/zoo_data/models.py
@@ -112,25 +112,29 @@ class CommonData(models.Model):
 class Entity(CommonData):
     schema = models.ForeignKey(
         'zoo_meta.EntitySchema',
-        verbose_name=_('schema'))
+        verbose_name=_('schema'),
+        on_delete=models.CASCADE)
     created = models.ForeignKey(
         Transaction,
         blank=True,
         null=True,
         verbose_name=_('created'),
-        related_name='created_entities')
+        related_name='created_entities',
+        on_delete=models.CASCADE)
     modified = models.ForeignKey(
         Transaction,
         blank=True,
         null=True,
         verbose_name=_('modified'),
-        related_name='modified_entities')
+        related_name='modified_entities',
+        on_delete=models.CASCADE)
     deleted = models.ForeignKey(
         Transaction,
         verbose_name=_('deleted'),
         blank=True,
         null=True,
-        related_name='deleted_entities')
+        related_name='deleted_entities',
+        on_delete=models.CASCADE)
     meta = JSONField(
         blank=True,
         null=True,
@@ -160,33 +164,39 @@ class Entity(CommonData):
 class Relation(CommonData):
     schema = models.ForeignKey(
         'zoo_meta.RelationSchema',
-        verbose_name=_('schema'))
+        verbose_name=_('schema'),
+        on_delete=models.CASCADE)
     left = models.ForeignKey(
         'Entity',
         verbose_name=_('left'),
-        related_name='left_relations')
+        related_name='left_relations',
+        on_delete=models.CASCADE)
     right = models.ForeignKey(
         'Entity',
         verbose_name=_('right'),
-        related_name='right_relations')
+        related_name='right_relations',
+        on_delete=models.CASCADE)
     created = models.ForeignKey(
         Transaction,
         blank=True,
         null=True,
         verbose_name=_('created'),
-        related_name='created_relations')
+        related_name='created_relations',
+        on_delete=models.CASCADE)
     modified = models.ForeignKey(
         Transaction,
         blank=True,
         null=True,
         verbose_name=_('modified'),
-        related_name='modified_relations')
+        related_name='modified_relations',
+        on_delete=models.CASCADE)
     deleted = models.ForeignKey(
         Transaction,
         verbose_name=_('deleted'),
         blank=True,
         null=True,
-        related_name='deleted_relations')
+        related_name='deleted_relations',
+        on_delete=models.CASCADE)
     meta = JSONField(
         blank=True,
         null=True,
@@ -205,11 +215,13 @@ class Relation(CommonData):
 class Log(models.Model):
     entity = models.ForeignKey(
         'Entity',
-        verbose_name=_('entity'))
+        verbose_name=_('entity'),
+        on_delete=models.CASCADE)
     transaction = models.ForeignKey(
         'Transaction',
         null=True,
-        verbose_name=_('transaction'))
+        verbose_name=_('transaction'),
+        on_delete=models.CASCADE)
     timestamp = models.DateTimeField(
         auto_now_add=True,
         db_index=True,
@@ -276,7 +288,8 @@ class Job(models.Model):
         'Transaction',
         verbose_name='transaction',
         null=True,
-        blank=True)
+        blank=True,
+        on_delete=models.CASCADE)
 
     state = models.PositiveIntegerField(
         verbose_name=_('state'),
diff --git a/zoo/zoo_meta/models.py b/zoo/zoo_meta/models.py
index 026059b..b739d45 100644
--- a/zoo/zoo_meta/models.py
+++ b/zoo/zoo_meta/models.py
@@ -165,11 +165,13 @@ class RelationSchema(CommonSchema):
     left = models.ForeignKey(
         EntitySchema,
         verbose_name=_('left schema'),
-        related_name='+')
+        related_name='+',
+        on_delete=models.CASCADE)
     right = models.ForeignKey(
         EntitySchema,
         verbose_name=_('right schema'),
-        related_name='+')
+        related_name='+',
+        on_delete=models.CASCADE)
     is_symmetric = models.BooleanField(
         default=False,
         blank=True,
diff --git a/zoo/zoo_nanterre/models.py b/zoo/zoo_nanterre/models.py
index 6ba8264..d01d32b 100644
--- a/zoo/zoo_nanterre/models.py
+++ b/zoo/zoo_nanterre/models.py
@@ -43,11 +43,13 @@ class Duplicate(models.Model):
     first = models.ForeignKey(
         'zoo_data.Entity',
         verbose_name=_('first'),
-        related_name='+')
+        related_name='+',
+        on_delete=models.CASCADE)
     second = models.ForeignKey(
         'zoo_data.Entity',
         verbose_name=_('second'),
-        related_name='+')
+        related_name='+',
+        on_delete=models.CASCADE)
 
     score = models.DecimalField(
         decimal_places=2,