There is no anti-spam for comments, but there are several hacks to add a captcha. I used this one.
A plugin exists in order to provide link prefetching hints that Mozilla-based browsers interpret to increase the speed of image navigation.
kses($_POST['comment'], $allowed_tags) into
$_POST['comment'] at zp-core/functions-controller.php:151&156 because the
allowed_tags option is not well defined and it bugged when submitting comments
Removed obligation to give email address when posting comment at zp-core/class-image.php:303
Removed checkforPassword() at zp-core/template-functions.php:next_album, because it was buggy and is better like that
Added .htaccess “Deny (all)” in folders protected by password
Modified the default:light theme to add comments feed link, latest photos and statistics on home page, image titles in album page, thumbnails prev/next and image count and dates in image page …
Disabled keyDown events when ajax-editing in zp-core/js/ajax.js, because the theme allows to navigate through images using key arrows, but it also changed image when navigating through text when editing descriptions.