user4109: Specifically I'm talking about this question, where the accepted answer is fantastic. Sources, graphs, full of useful information, well-written and easily understandable. 
Unfortunately it's not complete. It's not like radiotrophic fungi are common knowledge, they're kind of a corner case with lots of fairly recent work. However the question is trying to get at the existence or nonexistence of exactly that corner case.
So my question is this: What should I do with this?
Do I:

Give a separate answer?
Edit the answer as is?
Should I downvote the answer for being not-quite-correct? (I really don't want to, it's a very good answer)
Comment?

If it was a nearly-complete question that was correct but perhaps left out something I thought should be maybe mentioned, I'd comment. If it was completely wrong, I'd downvote and answer myself. I'm a bit stuck because the answer is missing only one detail, but the detail is (imo) crucial.
What's the polite/correct thing to do? 
(I've given a separate answer, but mostly by reflex. I don't necessarily favor that approach)

user5144: I think you did react in the perfect way: Add another answer to the question and simply cover the missing parts. As far as I understand it, downvotes are for wrong or low quality answers.
I think there is no need to edit the existing answer (if there are no errors in it) and you can get the reputation for your part of the answer. There is also no need to have all the information in one answer.

4109: <p>Specifically I'm talking about <a href="https://biology.stackexchange.com/questions/26418/do-electromagnetic-waves-outside-the-visible-spectrum-have-any-role-in-photosynt/26425#26425">this question</a>, where the accepted answer is fantastic. Sources, graphs, full of useful information, well-written and easily understandable. </p>

<p>Unfortunately it's not complete. It's not like radiotrophic fungi are common knowledge, they're kind of a corner case with lots of fairly recent work. However the question is trying to get at the existence or nonexistence of exactly that corner case.</p>

<p>So my question is this: What should I do with this?</p>

<p>Do I:</p>

<ul>
<li>Give a separate answer?</li>
<li>Edit the answer as is?</li>
<li>Should I downvote the answer for being not-quite-correct? (I really don't want to, it's a very good answer)</li>
<li>Comment?</li>
</ul>

<p>If it was a nearly-complete question that was correct but perhaps left out something I thought should be maybe mentioned, I'd comment. If it was completely wrong, I'd downvote and answer myself. I'm a bit stuck because the answer is missing only one detail, but the detail is (imo) crucial.</p>

<p>What's the polite/correct thing to do? </p>

<p>(I've given a separate answer, but mostly by reflex. I don't necessarily favor that approach)</p>
 5144: <p>I think you did react in the perfect way: Add another answer to the question and simply cover the missing parts. As far as I understand it, downvotes are for wrong or low quality answers.</p>

<p>I think there is no need to edit the existing answer (if there are no errors in it) and you can get the reputation for your part of the answer. There is also no need to have all the information in one answer.</p>
