diff --git a/src/black_holes/EAGLE/black_holes.h b/src/black_holes/EAGLE/black_holes.h
index aaeed5783429bb24318dfad116d4c1192b64f9c2..e9c873f69b40cb2bebfe02355a50a99ab37d3503 100644
--- a/src/black_holes/EAGLE/black_holes.h
+++ b/src/black_holes/EAGLE/black_holes.h
@@ -55,6 +55,7 @@ __attribute__((always_inline)) INLINE static void black_holes_first_init_bpart(
   bp->time_bin = 0;
   bp->subgrid_mass = bp->mass;
   bp->energy_reservoir = 0.;
+  bp->formation_time = -1.;
 }
 
 /**
diff --git a/src/black_holes/EAGLE/black_holes_io.h b/src/black_holes/EAGLE/black_holes_io.h
index ffd4a38a61ef8bd8f124128be7fe9a852634f52e..f794d7a298838eee8d6da6fd6ca75d59c8110677 100644
--- a/src/black_holes/EAGLE/black_holes_io.h
+++ b/src/black_holes/EAGLE/black_holes_io.h
@@ -61,7 +61,7 @@ INLINE static void black_holes_write_particles(const struct bpart *bparts,
                                                int *num_fields) {
 
   /* Say how much we want to write */
-  *num_fields = 5;
+  *num_fields = 10;
 
   /* List what we want to write */
   list[0] = io_make_output_field("Coordinates", DOUBLE, 3, UNIT_CONV_LENGTH,
@@ -74,6 +74,16 @@ INLINE static void black_holes_write_particles(const struct bpart *bparts,
                                  bparts, id);
   list[4] = io_make_output_field("SmoothingLength", FLOAT, 1, UNIT_CONV_LENGTH,
                                  bparts, h);
+  list[5] = io_make_output_field("SubgridMasses", FLOAT, 1, UNIT_CONV_MASS,
+                                 bparts, subgrid_mass);
+  list[6] = io_make_output_field("FormationTime", FLOAT, 1, UNIT_CONV_TIME,
+                                 bparts, formation_time);
+  list[7] = io_make_output_field("GasDensity", FLOAT, 1, UNIT_CONV_DENSITY,
+                                 bparts, rho_gas);
+  list[8] = io_make_output_field("GasSoundSpeed", FLOAT, 1, UNIT_CONV_SPEED,
+                                 bparts, sound_speed_gas);
+  list[9] = io_make_output_field("EnergyReservoir", FLOAT, 1, UNIT_CONV_ENERGY,
+                                 bparts, energy_reservoir);
 
 #ifdef DEBUG_INTERACTIONS_BLACK_HOLES
 
diff --git a/src/black_holes/EAGLE/black_holes_part.h b/src/black_holes/EAGLE/black_holes_part.h
index 0aa311ff8084b87e607f6ccbf3d1cce7b15b53ce..bbb19936b6d33c2b42279f93d53e5fc31d60491d 100644
--- a/src/black_holes/EAGLE/black_holes_part.h
+++ b/src/black_holes/EAGLE/black_holes_part.h
@@ -63,6 +63,16 @@ struct bpart {
   /*! Subgrid mass of the black hole */
   float subgrid_mass;
 
+  /*! Union for the formation time and formation scale factor */
+  union {
+
+    /*! Formation time */
+    float formation_time;
+
+    /*! Formation scale factor */
+    float formation_scale_factor;
+  };
+
   /*! Energy reservoir for feedback */
   float energy_reservoir;