I've noticed that Anna will sometimes only use one pectoral fin to swim around. I freaked the first time I noticed because I though something had happened to one. Nope, she just held it to her body. She'll swim like that for maybe 5-10 minutes and then back to normal swimming she goes.
She doesn't act like she is in distress when she does it, and she has been acting normal and eating fine otherwise.

Is this just something fish do sometimes? Could something be wrong or is it just an odd quirk of hers?