Green Corys Not Acting Right

[DiddleBug]

My green corys have been hardly moving at all lately.  They eat when I put food in (frozen bloodworms, frozen brine shrimp, 2 types of pellets, and flakes), but then they just lay there.  The water quality is fine (0 ammonia, 0 nitrates, 7.0-7.5 ph) and the temp is 76-78.  I've been doing 1/3 water changes every 2-3 days as I'm conditioning them.  The tank has been running for a year or two and fish have been fine in it till now.  The tank is a sanded 10 gallon and fairly well planted (fake plants).  What am I doing wrong?  

 

[CoryLover95]

Corys aren't the most active fish due to the fact that instead of scales they have hard plates on their bodies which restricts their movement.  Check when the lights are off - mine just lay there during the day but go crazy at night.

 

[Shaddex]

Corys aren't the most active fish due to the fact that instead of scales they have hard plates on their bodies which restricts their movement.  Check when the lights are off - mine just lay there during the day but go crazy at night.

 
Agreed.  Lights out = Manic Corys