So I'm sort of stumped as to what's causing this, and what to do to fix it.

I have 6 discus. 2 red colored ones, and 4 blue/green ones.

The 4 blue/green ones, have just started (as of last night) to beat on the reds. Serious nipping, one's fins are kinda tore up. The 4 will nearly swarm one or the other red and pick at it.

I pulled the two reds from the tank, but I'm at a loss as to why they're doing it. There's plenty of places to hide, there's never been a problem before now, and there hasn't been any changes or additions or much of anything.

It doesn't seem like breeding behavior. So yea. Dunno what to do with them.

This sounds like a question for pops. Ill try to get him back on here.

Only thing I can think of is that the blues are all males and the reds aren't.

thats the only thing that makes sense to me also, but i do not keep discus, gl

If wesleydnunder stops in he could probably help you out with this one. What size tank are they in?

Hello All,

S_F We need more info.

What size tank?, tank mates? , tank location?, water parameters. Over all health of Discus.

We find that when you have agression with 5 or more Discus it is usually pecking order or spawning. Do not forget these are chilcids and act the same as Angels and most other Chiclids from that region.

They may be just mean fish!!

Their souroundings have a lot to do with the way they behaive, I see you removed the ones that we being picked on and that was smart . They would have probably perrished .

Your two reds may be ill, or you may have some very agressive females or males .
If I am not mistaken you picked up the 2.5" and if my calculations are correct they should be between 3.5 and 4" by now .

Keep the two seperated for a few weeks and then try to re introduce after they have regained their strength.

Call me or stop in if you have any questions.

The one flachen, is still on the smaller side, around 3.25" is actually one of the most aggressive of the lot, but everyone else is getting close to 4"

It was just the 6 of them and a few apple snails in a 55. The tank is in a fairly low traffic area. Water is good, I do near daily 20% changes. They get 2 feedings a day, one of flakes one of that recipe you gave me. There's some coverage/hiding spots if need be as well, but I've never seen them use them.

The only thing that's changed recently, and this was about 2 weeks prior to the fighting (maybe longer I don't remember exactly), was the light for the tank got replaced. I have no idea what the original bulb was, but it was the one that came with the hood. I replaced it with some generic ones from Lowes. The brightness is about the same but I'm sure the light color spectrum changed some. I would have thought that if that were the cause the aggression it would have happened sooner.

Except for getting beaten on, they were all healthy or at least were all acting and looking healthy. Right now, the one red who took the most damage is skittish and has been hiding a lot, but still comes out to eat when I feed them. I'm hoping since it seems like I caught it early enough that it just looks worse than it is.

The two reds are currently in a 20g alone and getting on just fine. I used a half dose of melafix for the fin damage, since I've had good luck with it for other cichlids.

I've never seen the pecking order work it self out in action. My experiences with other cichlids has always been one fish is picking fights. I've never seen a group go after one fish like that. I'm assuming since it was a group that it's not spawning.

I'll give them a month separate, and try them in together again. worse comes to worse, I just gotta keep them separated. Annoying, but that's how it works sometimes I guess.

Thanks for the help.

Will since there cichilds they probably will be aggresive to each other. I suggest adding some neon tetras, tiger barbs, dithers etc...