diff --git a/src/vbl_aquarium/models/urchin.py b/src/vbl_aquarium/models/urchin.py
index 028e977..f4f5028 100644
--- a/src/vbl_aquarium/models/urchin.py
+++ b/src/vbl_aquarium/models/urchin.py
@@ -116,6 +116,6 @@ class ParticleGroupModel(VBLBaseModel):
 # Utilities
     
 class ColormapModel(VBLBaseModel):
-    name: str
-    min: float
-    max: float
\ No newline at end of file
+    name: str = ''
+    min: float = 0
+    max: float = 1
\ No newline at end of file