I was in Roatan for 2 weeks in May. Now, we saw a few large grouper. I don't recall seeing any sharks. There were decent angel fish and morays (lots of morays). There were numerous smaller fish. Now, as far as it being "diminished", I don't know what your reference time frame is. The diving was quite good. Now I do see far more big grouper at Key Largo or Little Cayman.
As far as bugs, I think you must be refering to mosquitoes and no-see-ums. The first week I was there, the winds were pretty brisk so the insect problem was not really significant. The winds died down in the second week and the no-see-ums were a minor problem. I was lucky, I did not get much of a reaction to their bite. I understand that the biting insects can get quite a bit worse and many people bring their own insect repellant. Most of the time unless the insects are over the top, I just endure the bites.
As a caution, Roatan is in a malarial zone. I understand that the malaria problem is not that bad. However, if you have ever read about the problems one has with malaria, taking an antimalarial drug seems like a really a good idea.
