image titles in gallery

Hi, I have just created a gallery, I’m using twenty eleven theme… https://www.culturedcarpbaits.co.uk

I have lots of pictures to add,when u hover over an image the name of the file appears, with so many pictures to upload I don’t want this. Some I do (although I’m not too concerned if I can’t if its easier not to show details for all) and I know I can add a title/description to each image but is there a way I can stop the file name appearing when you hover over it? I am using a child theme + can access my style.css file.

Any help appreciated! Thanks