I use a Canon 7D with either a 100mm macro lens or an MP-E lens. Both on their own or with extension rings depending on what I am trying to photograph.
In terms of lighting, I find the onboard flash to be more pain than its worth.
Its position tends to just create a dark shadow due to the lens and the inevitable close up nature of the subject.
My solution has been to do one of the following
1. With fish fry I use a lens mounted ring light/flash, one that can be on permanently, something like
Then attach the ring flash to the macro lens and away you go.
2. With smaller items like eggs or shrimp fry it is still difficult to light them with the ring light attached to the lens.
For these smaller subjects, I place the ring flash on a table and then suspend the subject on a piece of slide glass an inch or so above the ring light (or just on the ring light if I am feeling lazy).
Then using a tripod, shoot vertically down onto the slide and I have my photo (back lit so you can see detail, but loose some colour).
To focus with the extension rings and the MP-E, I lock the tripod then put weight on the height adjustment, to move the entire camera and lens fractions of a MM to get close to focus (middle of the water drop).
For final focus, it generally means pressing the table that the subject is on with my thumb about a foot from the subject. This allows for a distortion and for focus to be achieved.
With the live and moving subject, depth of field is very difficult, so I don't even bother.
This shot is with the slide placed on the ring flash, you can see the texture of the ring flash in the background
This shot is raised up from the ring light
Hope this helps
<message edited by CaptCrash on Thursday, December 3, 2015 7:50 PM>