Its a bug related to the blueprint bug. To avoid it in the future never use the pause menu to quit Subnautica. For now close it from the dashboard. You can do this by pressing the home buttton after you save and then press START on Subnautica and select quit.
If you need to fix the fish info and blueprints now you can do this by uninstalling and reinstalling Subnautica WITHOUT deleting your save data.
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If you need to fix the fish info and blueprints now you can do this by uninstalling and reinstalling Subnautica WITHOUT deleting your save data.