Firstly, motivation for my question.
One, anthro wiki.

General: anthro

The term "anthro" is short for "anthropomorphic", which means attaching Human traits like intelligence and personality to non-Human things like animals and inanimate objects.

As this accurately describes most furry characters, "anthro" is commonly used to describe a bipedal furry character, ones whose nonhuman-to-human appearance ratio rates about 45% to 75%.

It is unnecessary and self-defeating to tag any and all posts with anthropomorphic characters anthro --
Exception

The tag should only be used on pictures that have feral animals in addition to one or more anthro characters. If an image has only anthro characters, don't apply this tag.

Two, anthro -feral has about 17*150 wrongly tagged pics.

So, the question is - is there a possibility to create implications with negative tags? If it was possible, it would be simple to replace bold fragment with implication:
-feral -> -anthro

No, that is not possible.

don't worry about anthro - feral :) tha'ts on my list of tags to clean up over the next few weeks. I need to reaquaint myself with some of the tools I have available to me.. may or may not have a way to clean up the tag easily... but I don't recall for sure. o.<

If nothing else, I have tag scripts that can make that a lot faster <3

Man, I wish I could negathis implicate things.