It’s not been an easy road to acquire specialised knowledge, skills and training as described by a colleague, even in the US. So, they have compiled a list of training providers and their courses on their blog.
Check it out here:
http://avsnca.com/aquatic-veterinary-medicine-resources/comment-page-1/
There will also be a couple of courses being run in Australia this year; in July (https://thefishvet.com/2013/01/11/2013-frdc-australasian-scientific-conference-on-aquatic-animal-health/)
and another in August (https://thefishvet.com/2012/12/28/the-24th-international-conference-of-the-world-association-for-the-advancement-of-veterinary-parasitology-will-be-in-perth-australia/).
Also, join WAVMA to network with other fish vets.