Cichlid swimming sideways

Question
I have two Jack Dempsey Cichlids (one 6 inches, the other 4) in a 30 gallon tank.  We also added 3 Convict Cichlid babies (about an inch long) about a month ago. The smaller of the Jack Dempsey has been hanging out near the filter for the past 2 days, and when it does swim it is swimming sideways.  We have had the 2 fish for about 2.5 years and they have been pretty healthy in a clean environment.  We had a power outage 2 days ago that lasted for 6 hours (the pump was off), but that is the only change.

Answer
Hi Kim,
  Is it possible that the larger Jack Dempsey is picking on the smaller one?  That is the most likely cause for problems.   

  The power outage is unlikely to have had any significant long term effect.

-- Ron
  rcoleman@cichlidresearch.com
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