Serial Dempsey

[benzjamin13]

I've seen it with my own eyes at JCashion's apt. Its really weird. Basically about two seconds after the lights go out its like Dr. Jekyl and Mr. Hyde, the Jack just flips a switch and starts beating the piss out of the oscar!! Weirdest thing i've ever seen. Why would a fish change its personality as soon as the lights go out????? :WTF:

anyone got any ideas?

It feels more comfortable in the dark. It gives the sense that they're hidden and if the dempsey attacks anything the other fish won't see it as well in the dark to attack back.

 

[MaJiKTeRRoR]

Maybe he doesn't like the light. My fronts hate light I only have 1 of my 3 lights on at a time on my 130.

 

[ashdavid]

Right now they're in a 55. Oscar's about 10". Jack's about 8".

That is your problem right there, fish with that nature and size should be housed in a bigger tank to appease aggression. There is probably nothing you can do until the bigger tank is up and running.