SCSI tape devices are named /dev/st0, /dev/st1, etc.
In general /dev/tape is a symbolic link to /dev/st0.
If your tape really is /dev/st0, you can add that symbolic link to /dev/tape by
ln -s /dev/st0 /dev/tape
Anyway, you can ignore /dev/tape and only use /dev/st0.
mt (and others) can use the device specified by the variable TAPE as the default device, so
$ export TAPE=/dev/st0
$ mt status
For your convinience, put that export TAPE at your shell rc file.