Fish summoned on water render on their side for a single tick

The bug

Fish summoned underwater (using /summon, spawn egg or bucket) render on their side for a single tick, causing flashing. This can be more easily seen using the /tick freeze command.

To reproduce

1. Run /tick freeze.

2. Use a fish (e.g. tropical fish) spawn egg against a block underwater.

3. The fish is rendered on its side.

4. Run /tick step.

5. The fish is rendered correctly.