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Odd yellow perch movements

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#1 midwest

  • NANFA Guest
  • Indiana

Posted 03 January 2020 - 09:46 AM

I have a 125 tank that has 2 yellow perch (about 6 inches) 2 hybrid blue gill (about 4-5 inches) 5 small long ear (2 inches) and a small yellow bullhead catfish (4 inches). Tank has been running since October and so far everything has been great. It is lightly planted and water parameters are where they should be.  The last couple weeks I have noticed one of the yellow perch will swim toward the bottom, turn to his side and then dart off real quick scraping his head against the gravel.  He will do the same against some of the rocks and driftwood.  He will do it 4 or 5 times in a row and then swim off somewhere and settle to the bottom.  Anyone ever seen anything like this?

#2 littlen

  • NANFA Member
  • Washington, D.C.

Posted 03 January 2020 - 12:11 PM

Yes, it is a known behavior called "flashing".  It is typically done for 1 of 2 reasons that I've seen.  The first being some sort of discomfort on their skin/slime coat.  It can be used as a way to essentially itch themselves or knock off an external parasite that is causing irritation.  The other reason (less likely IMO with your set up) is a territorial display to impose on intruders or rivals.  Yellow perch are very passive in my experience, so I wouldn't think it is trying to bully or show off for any other species in your tank.  I absolutely could be wrong though.  As long as you don't see other fish doing any flashing, I would not be too concerned about external parasites.  You could add a little aquarium salt if you are suspicious it may be an irritant and see if that helps.

Nick L.

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