Curley_gin,
We're going back to Fiji in October. We were there last March'ish and loved the diving. We were in the Somosomo Strait and the soft corals stole our hearts! Signed up immediately to go back and am somewhat comfortable doing so.
Reason for the "somewhat" is not what you're asking for. We did not see "big" stuff. But the soft (and to a degree) the hard corals were enough for us to sign up for a return trip, and from that perspective, I cannot wait to return.
All that said, I have heard distressing reports about the health of the soft coral in Somosomo. I pray that the reports are not correct ... we are booked and billed to go!
If the soft corals are still happening you're in for a great trip. But, either way, I don't think that you could count on "big fish" encounters. While it could happen ... the soft coral is the big attraction should you decide to head out to Taveuni, which, of course, it not Marlin Bay. After all, there are over 300 islands in the Fiji chain! Just my two fifth's of a nickel ...
Hope this helps,
bearingboy