My friend has a problem, he was unable to buy more tanks because of his limited neighbours.
I suggested this solution for him:
Go to Fishville and click on My Neighbours. You will be able to see who you can add to be your neighbours.
Or a simple method, log into Facebook and place this URL into your internet browser.
You should be able to see your list of neighbours and who you can add to be your neighbours.
This is the shortest way I know how to add someone or to increase your neighbours...
Getting 8 tanks give you an award!