On the product details page for fisheye it suggests that github and mercurial can be used - however other documentation I've seen suggests otherwise - can you please clarify?
The actual answer to your question is "no"
This hasn't been answered particularly well by Atlassian. If you have an hour or so take a look at the epic comments on https://studio.atlassian.com/browse/JST-2090 and try to work out what the answer is (or even the question).
We are sorry about that mistake. The team in charge has been contacted for update.
Our FishEye is currently configured only with SVN. However, we expect an integration with other repos such as GitHub in the next coming months as the OnDemand Product Manager stated in the ongoing request to include these repos.
Please do watch the ongoing request about this matter at: https://studio.atlassian.com/browse/JST-2090
In the other hand, JIRA OnDemand includes a bitbucket & GitHub Connector plugin, that you may want to try while waiting. Below links provide more details:
Hope that helps.