I understand nicknaming the baby before it's born, and the couple using that occasionally between themselves- jellybean, or pip, or what have you.
However someone on my FB has nicknamed their baby Li'l Fishy, and they have referred to it as Li'l Fishy constantly. I thought nicknames happened organically, but friends and family were informed of the bump nickname they had decided upon. She is a bit of a pregzilla tbh, so I'm probably BU purely due to the amount of times I have read and heard the name Li'l Fishy over the past few months, but I was quite surprised when they announced the baby as "Baby Li'l Fishy"
That was a few days ago, no other name yet... Maybe they are going to stick with the nickname forever!