It looks like you need to do this first (oldest syntax provided):

   INFORMIXDIR=/usr/informix ; export INFORMIXDIR

You can find out what an error number means using:

   $ finderr -25553

   -25553  Sqlhosts file not found or cannot be opened.

   The sqlhosts file is required to determine information to establish
   connection to a local or remote server. Create an sqlhosts file in the
   directory $INFORMIXDIR/etc according to the format that the manual for
   your database server product describes.

Regards,
Doug Lawry
www.douglawry.webhop.org