There are many alternatives to gThumb for Linux if you are looking for a replacement. The best Linux alternative is XnView MP. It's not free, so if you're looking for a free alternative, you could try digiKam or Shotwell. If that doesn't suit you, our users have ranked more than 50 alternatives to gThumb and many of them are available for Linux so hopefully you can find a suitable replacement. Other interesting Linux alternatives to gThumb are qView (Free, Open Source), Gwenview (Free, Open Source), qimgv (Free, Open Source) and Eye of GNOME (Free, Open Source).
digiKam is an advanced digital photo management application which makes importing and organizing digital photos a "snap". The photos are organized in albums which can be sorted chronologically, by folder layout or by custom collections.
Eye of GNOME is the official image viewer for the GNOME Desktop environment. With it, you can view single image files, as well as large image collections. The Eye of GNOME supports a variety of image file formats.
PhotoQt is a simple, yet powerful and good looking image viewer, written in Qt, published as open-source, and completely free. Photo comes with a variety of features. Most features you would expect from a image viewer should be there.
QuickViewer is a graphic image viewer for comfortable browsing of many images. This software performs reading of image data in advance. And drawing the imported image data on the screen with OpenGL. You can browse images with much smoother response than ever before.