I shoot nikon. But I often use the very similar nikon 60 mm macro. On a crop sensor camera, the 60 works like a short telephoto. It works well on small fish. For close ups, the macro lens needs to get very close, for maximum effect. It is so close that it is hard to light the subject with the strobes. If the subject has any awareness at all, it will move. I often use a Subsee wet lens to get a bit more magnification. The lens is very good. It focuses fast. It is fun to use. If your camera is full frame, the 60 is wide enough for angel fish and anything smaller.
the other choice is the 105 macro. It is better for close ups because you have more standoff room. It is very nice for taking shots of small skittish fish like jawfish, damsels, butterfly fish, chromis and so on.
i generally shoot manual. With macro, I usually set my strobes at less than full power. I shoot a shutter speed of about 1/200, an ISO of about 200, and an F of 8 or higher.
If I had just one lens besides a wide angle, I would use the 60 with the wet diopter Subsee. If I wanted to shoot pretty much only tine subjects at true macro, I would use the 105.