Do read the article and follow the link to
Science. It is really interesting and not really helpful to creationists.
To summarise:
HSP90 canalises development - when it is suppressed, the fish are more sensitive to genetic variations.
When the variations are expressed, they become available to selection.
Eventually the fish reach a state where the new form is stable even when HSP90 is working. But it is evolution that gets them there.
Oh, creationists can try to use it in their excuses, but all it is is a new way in which evolution can work. It doesn't actually demonstrate anything which would help them.