quite possibly, i'm not sure how the macro works but i think it moves the lens' so that i can focus closer, that could possibly cause it to wear out, altho it's a complete guess!
Also if you mount it on a tripod, try using the self timer, this will prevent any camera shake from you pressing the button.
i have no idea about sony camera's, but if there is an option to change the ISO setting, try increasing it, wouldnt go any higher than 400 tho. Increasing it, will increase how sensitive the CCD is to light, but does produce a grainier image. so experiment.
Also when you're photographing in low light, a slower shutter speed will allow more light in but if your fish move they will blur. To a cerain extent you can use the aperture, if you can not set it manually, zooming all the way out will alow a larger aperture on most cameras...
hope this helped
