Discus aggression (pecking order I think)

  • #1
Hello discus keepers, for around a week now, one of my turquoise discus has been taking a beating by another turquoise in the tank. He lost lots of color and hides. He eats when I feed, but the bully chases him after feeding. If he comes out of his hiding spot, the bully chases and pecks him, he doesnt fight back. What could I do to stop the bully, and help the turquoise? Thanks
Tank Specs:
40 gallon
Fluval 50
heat set to 84
4 discus, pigeon mix, Albino yellowish, 2 turquoise
3 Julie cory cats


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  • #2
The territorial aggression is typical for Cichlids. There is always a low fish in the hierarchy. Constructing new hiding spots & dimming the lights might help.
86 ssinit is our Discus guru. Maybe he will chime in.
86 ssinit
  • #3
This type of chasing happens. If you remove the one being chased and put n a qt tank it will get a chance to destress and hopefully recover. Now what the bully does next will tell you what’s up. If it chases another discus it’s going to continue and it will need to be removed. If the tank goes back to normal leave the chased fish in qt for about a month change around the decor of the tank and put it back in and see what happens. Hopefully nothing.
  • Thread Starter
  • #4
Thanks, I guessed it was a territorial problem, the bully only attacks others when they are in the way. I have a 10-gallon right next to the 40, which I might tear down soon, and I can use it as a separation tank. I probably will separate the bully in the 10 gal.
86 ssinit
  • #5
There’s a lot to keeping discus. If kept right they will grow to 6”. A 40g isn’t the best size for discus. Makes a good qt tank though. A 75 would be a better size tank.
How long have you had them?
  • #6
I hate to say this but your tank is simply not big enough. I have my 5 Discus in a 150g and if I had a pair the minimum sized tank would be 80g. Discus need room to dance, and get away from each other.
  • #7
I have not had any luck with "Timeouts", rearranging the tank and moderately planted tanks with hides. I tried numerous times when I kept Discus along with Angels and Africans. I thought it worked a couple of times but... as mentioned its nature...

Good Luck!
  • #8
I have not had any luck with "Timeouts"
The concept doesn't work on animals in general. Maybe apes, certain cetaceans or birds, but if you put a fish in timeout it will only "behave" after it until it has recovered from the stress of netting. That's it.
  • #9
I do agree with Itiwhetu that a 40 gallon tank is not big enough for four discus and being cramped will exacerbate aggressive behaviour and it will be difficult for the targeted fish to hide. But even in a large tank similar problems can still occur. I have just been dealing with this recently with a particular angelfish that has been kept with 5 others in a tank that is over 150 gallons. For nearly two years the 6 have got one OK apart from normal bickering, though one always attacked one other particular fish which did not "answer back". It didn't seem to be a big problem as there was room to get away, and the two of them seemed to keep together most of the time anyway. But recently the aggressive one has become even more aggressive, and always targeting the same fish to the extent that it was always hiding except to come out for food, then it would be chased back again quickly just as you describe with the discus. I decided to move the offending angelfish to another tank. I was thinking of trying time out but have often read that it doesn't work. Everything in the angelfish tank is so much more peaceful now.
86 ssinit
  • #10
I didn’t recommend removing the bully I said remove the beaten fish to give it a chance to recover. With my discus when young this has worked 3 out of four times. Next being juveniles and keeping the weaker one out of the group for a month gave it a chance to destress and grow. These 3 went back in to no problems. The fourth was just stunted but even it upon going back had no problem. The main group had also grown. Most times a bully that needs to be removed is an adult. Not sure how old these discus are but look to be about 3.5” so I’m thinking juveniles.

As to the size of the tank. Being 40g it will need more maintance. Not knowing what the op knows about discus I’m thinking they’ve read up on them and know about the daily water changes and filter maintenance. 4 in a 40 is very doable. Being 3.5” fish this would be the recomended size tank to grow them out. You’d only be changing 20g a day to get them big. Than moving them into a bigger tank at 5-6”. But many keep in 40g tanks.
  • #11
Just as a side note. My Discus get a 25% water change every 4 days and the two internal filters get their pads squeezed at the same time. Not much more work than a normal tank.
  • #12
Yes. Timing out a "bully" (more aggressive or dominant) fish doesn't work.
What does work is QT the picked on fish for a month, great water quality, destress and heal and extra small feedings to put on body mass and size. This will increase how it feels, increase its condition, and increase its boldness. In a lot of instances the hierarchy shifts and that low fish is no longer low and can stand up for itself or stand up with the others, and in a perfect world everyone is evenly matched or at least can gang up and give the dominant aggressive fish a good workout and nobody gets hurt anymore from sparring.

It's when one becomes too timid, and kept too weak and a tank is too tight for the group, the low man can get picked on relentlessly and eventually misses out on food and stays held back. The other fish might not pick on him but they won't get involved either because they are ok with their position.

It's sort of a rivalry, from my experience with angels a dominant male will do this type of thing to a 2nd dominant fish early on, in order to hold the power and keeps him smaller and weaker so it can't challenge the leader. Discus are more sensitive but not all that dissimilar in their social order.

QTing the weak fish to heal and gain mass is the only way I know to get the hierarchy to shift with any success. to where the QTed fish returns bigger stronger and more confident and now can hold his own or even win, at that point, if it wins it may do the same thing back to that dominant fish and keep him held back, or he'll put up enough of a fight that the others will see an opportunity for a power change and join in against the dominant fish, and if that happens, the group keeps the dominant fish in line, and the dominant fish keeps the order and knows the group can knock him down if he gets too aggressive.
As it stands the dominant fish has no line, he pushes and everyone backs down and doesn't want to get involved, and he holds back the most likely source of a challenge that could take top of the group from him.

Anyways. I prefer to QT the most beat up or the low man for a month, if it's another dominant fish they recover quickly with a destress and put on mass and get in better condition. It might not work the first time, it might need to be done again and get more weight on him with some more time. But I've had it shift and then everyone gets along happen more times than a fish dying or needing to rehome the most aggressive fish.
Neither of which really solves the issue.
86 ssinit
  • #13
Just as a side note. My Discus get a 25% water change every 4 days and the two internal filters get their pads squeezed at the same time. Not much more work than a normal tank.
For Itiwhetu this works and will work. 5 discus in a 150g tank. The maintenance will be less. But they are adult discus and still getting new water every 4 days. 4 in a 40g will need new water daily.

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