When moving with two solid blocks on either side, dolphins will sometimes take block suffocation damage. The place where they are taking damage is posted below.
MC-128315
Dolphins take damage in corner of solid blocks
Resolved
Awaiting Response
3
Is this still an issue in the most recent versions (currently that is 1.13.2, or the latest snapshot 18w46a) of Minecraft? If so, please update the affected versions and help us keeping this ticket updated from time to time. If you are the owner/reporter of this ticket, you can modify the affected version(s) yourself.