I’m not having any fish or squid spawn in server?

I’m playing a server that I started in Minecraft 1.13 and the server had fish and squid spawn a lot then but now that the server is running on Minecraft 1.14 none them spawn.

Does anyone know how I could fix this?

Do I have to regenerate world? If so is there any way we can keep old world, like convert it to 1.14?