How do you convert settlements with no rural tiles?

[playshogi]

For example, tiny island settlements often have no rural tiles.

 

[ProMeTheus112]

For example, tiny island settlements often have no rural tiles.

They should have at least one fishing boat no? Then you can convert the fishing boat. I don't know what happens if a player settles a town, immediately converts it into a city and adds a specialist instead of a rural tile.

 

[Krikkit1]

They should have at least one fishing boat no? Then you can convert the fishing boat. I don't know what happens if a player settles a town, immediately converts it into a city and adds a specialist instead of a rural tile.

I think there is a size requirement either for becoming a city or using a specialist... or both