Fancy Guppies, other community fish all facing same direction in tanks

Question
Hi,
This isn't really a problem so much as a curiosity. I have two 20 gallon tanks on opposite sides of a large room. One is a community tank with only a few fish remaining, all of which are very old. The other is a thriving fancy guppy tank with tons of fish of all ages, including a few weeks old. For some reason, every night and sometimes during the day, I notice that all of the fish in both tanks are concentrated in a corner of the tank, facing in one direction. This is in both tanks, with all of the fish facing the same direction. The guppies crowd into a corner and swim towards nothing, while the community fish just kind of hang out in that same corner all day and night. Is there a reason for this?
Thanks!
- Jessica

Answer
Hi Jessica,
 There could be several reasons. Is that where the heater is in the tank, or where the filter is blowing the warmer water?   Or, are they watching you? (Fish do that a lot).  

-- Ron
  rcoleman@cichlidresearch.com
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