The goldfish.png image file was initially attached to the Goldfish DITA map. Its originId is amazing_goldfish.
The Animals DITA map already has the pufferfish.pdf file attached to it in its two instances, Novice and Intermediate.
To add the goldfish.png image file to the Animals DITA map in its Novice instance, use its originId (retrieved in the Metadata journal) as follows:
<?xml version='1.0' encoding='utf-8'?>
<controlFile>
<resources>
<resource>
<filePath>_animals.ditamap</filePath>
<instances>
<instance>
<filePath>Novice.ditaval</filePath>
<attachments>
<attachment>
<originId>amazing_goldfish</originId>
</attachment>
</attachments>
</instance>
</instances>
</resource>
</resources>
</controlFile>