Firebird Sql 2.5 for #Apple #MacOSX is out, Minimum supported version is 10.6 Snow Leopard
NOTE :: To make the new engine work properly under multi-threaded conditions we had to use Grand Central Dispatch, which was first released in MacOSX 10.6 (Snow Leopard). MacOSX users should be aware that Firebird 2.5 will run only on MacOSX 10.6 or higher versions. If you want to use an earlier version of OSX you will need to use an earlier version of Firebird.
Download from usual location :