I ended up meeting/talking to this old guy yesterday who's kept Oscars for some 20+ years and was telling him about the gigantic one that hates everyone except the channel cat.

He gave me a very interesting tip that so far actually seems to be working.

Besides re-arranging the tank completely to get rid of any territory disputes, he would clip a pan light to the side of the tank and shine it into the side at an angle. He'd leave it like that for a few days to a week, depending on what they were. He said he's done it with other cichlids and it's worked just fine too, but his big thing was oscars so he didn't know how well it would work on anyone else.

So, I decided to give it a try with the cranky one here, and so far it's actually working. It's only been about 8 hours so far, but no one has yet beaten on anyone or if they have there's no damage anyhow.

Sorry I didn't see this sooner.Sounds interesting is he still behaving? What exactly is the light doing?

Wow I missed this too they need to fix the new thread problem soon. Anyway did it work and what is it supposed to do exacly?

Did he give any reasoning to why the light stops the territory disputes?

Is it still working now?

He didn't have a good reason why it worked. I asked and he said that someone years ago in a pet store told him that trick and it always seemed to work for him. if I had to guess, with the lighting angle changed and everything moved around even if the fish remembered the items in the tank, the light makes it look different enough that it's new.

Or blinds them.

Honestly I have no idea. But i do know that the beastly oscar that was beating the everloving crap out of anything that went near the tank (besides the channel cat) is now happily getting along with two other oscars after doing a week with a light on the side.

Wow thats cool... Add some tinfoil barbs, silverdollas as dithers.

I wonder what the actual long term effects of the fish might be. It don't seem healthy to shine bright light in to the eyes of a fish. Prolonged light exposure might not be all that good.

Hmmm...Interesting but I wonder why exactly it works and for how long?

The issues with territory disputes and new additions tend to work themselves out in a week or two before everyone is mostly okay with each other.

As for the long term effects? I don't know. Even when the light was on, and it was only a 20w CFL bulb, they didn't have any trouble eating or getting around. It was only on one side of the tank as well, so I dunno. If it was too bright they could have looked away.

As far as I know it didn't blind anyone and everyone got along after, so I put it in the win column.

I guess it is not much different than having a light over the top of the tank as far as blinding or effecting the fish goes. It's just strange that it seems to work for you. Who would have thought...lol