Good models to use for converting and other things for fantasy are:
Fishmen:
The lizardmen model range are exllent models to use,
kemrian Ushabti are exellent models for water gaurdians,
High elf bolt or dwarf bolt throwers are great for shell throwers,
high elf
dwarf
The orc and goblins giant can be converted into a sea titan,
lizardmen cold ones (the new models) are great for lesser aqua beasts,
the lizard men carnosaur is a great model for an aqua beast,
http://uk.games-workshop.com/storefront/store.uk?do=Individual&code=99110208048&orignav=13
High elf chariots are great models for shell chariots,
