I am pretty sure that this is intended.
At the first screenshot, I captured 1 fish and then released it.
At the second screenshot, I captured the second fish and released it again, and then they created their own "family".
MC-196830
Fishes that were in the bucket won't go with their "family"
Resolved
Invalid
1
This report is invalid as your game was modified when experiencing this issue. In the attachments you've provided, I can see that you're using modifications and the bug tracker only handles reports that can be reproduced in a vanilla environment. If the problem persists without the use of mods, feel free to create a new report. Additionally, please see the Bug Tracker Guidelines for the minimum standards when submitting a ticket.