diff --git a/app/lib/activitypub/activity/create.rb b/app/lib/activitypub/activity/create.rb
index f991faa6a6..6b8a715330 100644
--- a/app/lib/activitypub/activity/create.rb
+++ b/app/lib/activitypub/activity/create.rb
@@ -559,7 +559,7 @@ class ActivityPub::Activity::Create < ActivityPub::Activity
     info = instance_info
     return false if info.nil?
 
-    %w(misskey calckey firefish).include?(info.software)
+    %w(misskey calckey).include?(info.software)
   end
 
   def misskey_searchability
diff --git a/app/lib/status_reach_finder.rb b/app/lib/status_reach_finder.rb
index 7bdc300e1c..8639a30a9f 100644
--- a/app/lib/status_reach_finder.rb
+++ b/app/lib/status_reach_finder.rb
@@ -159,7 +159,7 @@ class StatusReachFinder
   def banned_domains_for_misskey_of_status(status)
     return [] unless (status.public_unlisted_visibility? && status.account.user&.setting_reject_public_unlisted_subscription) || (status.unlisted_visibility? && status.account.user&.setting_reject_unlisted_subscription)
 
-    from_info = InstanceInfo.where(software: %w(misskey calckey firefish)).pluck(:domain)
+    from_info = InstanceInfo.where(software: %w(misskey calckey)).pluck(:domain)
     from_domain_block = DomainBlock.where(detect_invalid_subscription: true).pluck(:domain)
     (from_info + from_domain_block).uniq
   end
diff --git a/app/services/activitypub/process_account_service.rb b/app/services/activitypub/process_account_service.rb
index d7859ba92d..18277034cf 100644
--- a/app/services/activitypub/process_account_service.rb
+++ b/app/services/activitypub/process_account_service.rb
@@ -305,7 +305,7 @@ class ActivityPub::ProcessAccountService < BaseService
     info = instance_info
     return false if info.nil?
 
-    %w(misskey calckey firefish).include?(info.software)
+    %w(misskey calckey).include?(info.software)
   end
 
   def subscribable_by
diff --git a/app/services/delivery_antenna_service.rb b/app/services/delivery_antenna_service.rb
index 53bcc226e7..3d26321995 100644
--- a/app/services/delivery_antenna_service.rb
+++ b/app/services/delivery_antenna_service.rb
@@ -121,12 +121,7 @@ class DeliveryAntennaService
     when :public, :public_unlisted, :login, :limited
       false
     when :unlisted
-      if @status.local?
-        !@status.public_searchability?
-      else
-        info = InstanceInfo.find_by(domain: @status.account.domain)
-        info&.software == 'firefish' || !@status.public_searchability?
-      end
+      !@status.public_searchability?
     else
       true
     end
diff --git a/spec/services/delivery_antenna_service_spec.rb b/spec/services/delivery_antenna_service_spec.rb
index e9620dc083..224d448b1a 100644
--- a/spec/services/delivery_antenna_service_spec.rb
+++ b/spec/services/delivery_antenna_service_spec.rb
@@ -362,42 +362,4 @@ RSpec.describe DeliveryAntennaService, type: :service do
       expect(antenna_feed_of(antenna)).to include status.id
     end
   end
-
-  context 'with federated unlisted post' do
-    let(:visibility)     { :unlisted }
-    let(:searchability)  { :public }
-    let(:domain)         { 'fast.example.com' }
-    let!(:antenna)       { antenna_with_keyword(bob, 'body') }
-    let!(:empty_antenna) { antenna_with_keyword(tom, 'body') }
-
-    context 'when unknown domain' do
-      let(:software) { nil }
-
-      it 'detecting antenna' do
-        expect(antenna_feed_of(antenna)).to include status.id
-        expect(antenna_feed_of(empty_antenna)).to include status.id
-      end
-    end
-
-    context 'when misskey domain' do
-      let(:software) { 'misskey' }
-
-      it 'detecting antenna' do
-        expect(antenna_feed_of(antenna)).to include status.id
-        expect(antenna_feed_of(empty_antenna)).to include status.id
-      end
-    end
-
-    context 'when firefish domain' do
-      let(:software)       { 'firefish' }
-
-      it 'detecting antenna' do
-        expect(antenna_feed_of(antenna)).to include status.id
-      end
-
-      it 'not detecting antenna' do
-        expect(antenna_feed_of(empty_antenna)).to_not include status.id
-      end
-    end
-  end
 end