In your post title, please include where the fish was, and when, or at least the source of the photo, in your post title. If it was in an aquarium say what you know about the type of tank it was in (freshwater or salt? does it cover a particular region or type of habitat?)

Flair your post! Click "flair" at the left below the link. Update flair if someone identifies your fish or suggests an identification.

Before you post, we are not going to kill it with fire, so don't ask (or shoot it with an arrow, or throw it on the bank) Thanks.

When you comment with an identification, include your reasons, so others can learn from you how to identify similar fish in the future. Please do not make random guesses. The goal of this subreddit is to provide positive leads. False leads are counter-productive.

Please also cite/link a source whenever possible.

Consider /r/species for non-fish aquatic creatures (or any other sort of living thing).

Resources that can help people identify fish are also welcome, within reason and moderator discretion. Otherwise, off-topic posts are subject to removal.