How to recognize a predatory journal

There is a lot of  information out there, how to recognize a predatory journal (PJ), so there is no need to build an own list here. Just see the warning signs at or the 25 crits at PJs are big problem now, as they already entered Pubmed and even reputed journals can become a PJ over time. As a basic reference I would use the (outdated) Beall’s list and cross check with Thomson Reuters ISI listing. PJs do not behave like a normal journal – see also the 96 things publishers usually do.