Aggressive Behavior Impacting Tank Mates (What to do?)

[Corona99]

I have recently started my first Discus Tank and things were going well for the 7-10 days. All 6 new fish were shy initially but were gradually settling in. As the 6 new Discus became more comfortable and the pecking order started developing, one of the Pigeon bloods started picking on a Golden Diamond and Mellon discus especially during feeding times. The Mellon has been holding his own but the Golden Diamond is now hiding in the back of the tank, head down, and has totally stopped eating. He comes out to swim with the group occasionally but as I indicated looks distressed. As a result he/she is not developing and has lost a lot of color compared to 7-10 days ago. I do not see anything wrong with him physically but he is obviously not doing well compared to the other 5. The others are growing, eating aggressively and developing their typical behaviors.

65 Gallon Tank - 6 Discus are the only current Inhabitants
Water Parameters are good Ammonia 0, Nitrite 0, Nitrate 10
33% Water Changes Daily (so far)

What can be done here...
Suggestions.??

Photos Attached:
410 - Earlier Photo
414 - Photo today

[Oxboy]

Take him out and put him in a quarantine tank. Raise the temp to 90 and add a couple tablespoons of salt. Do a daily WC replenishing the salt each day. When he starts eating, reduce the salt over the course of a few days and get 2 more discus for the QT. In a month, introduce all 3 into the main tank.

And get (and keep) your main tank nitrates under 5.

P.S. gravel is bad for discus. Nitrates creep up too quickly and it harbors too much gunk no matter how much you vacuum.

[Iminit]

I just had this problem. I too say to remove either the stressed fish or the bully. Seems the bully is bothering more than one fish. I removed the non eater and put it in a 15 by itself /with a cory and SAE. Temp in high 80s and it started eating as soon as it was added. Kept it in there for a few weeks than moved to a bigger tank with it old tank mates and all is fine. I didn’t add the salt. I didn’t need it.

[Oxboy]

I just had this problem. I too say to remove either the stressed fish or the bully. Seems the bully is bothering more than one fish. I removed the non eater and put it in a 15 by itself /with a cory and SAE. Temp in high 80s and it started eating as soon as it was added. Kept it in there for a few weeks than moved to a bigger tank with it old tank mates and all is fine. I didn’t add the salt. I didn’t need it.

Supposedly the salt destresses.

[peewee1]

The aforementioned advices are good ones, Wayne.

[Iminit]

Oxboy I do use salt. But first or just use clean water. If after a few days and it’s still not eating than salt. For me it’s just been clean warmer water.

[BrendanJ23]

If it was me, I would not remove this fish as it can cause additional stress moving to another tank. I would be changing the tank decor to reset any territories, and upping the water changes. To me, removing fish from their familiar environment is a last resort. I would also be looking to remove or change your substrate as this will cause health issues in future.

[Corona99]

Thanks for your recommendations. I will give it a try.

[Corona99]

Thanks

[Corona99]

Thanks to all for the recommendations. I will give them a try. They agree with my thoughts as well. No one has mentioned any medication. Would there be any value here as a precaution?

[captainandy]

Always a challenge with no right answer. Helps to make a hiding place with plants. Usually stops.


Things that don't work:
Chase aggressor with a stick
Flash aggressor with flash light
Knock on the tank

[Iminit]

I say no to medication. It’s just stress. Clean warm 88 water will get him back. Your fish look great and strong. Even the stressed one. I do believe with a little time by itself it will start eating again. Where did you get your discus?

[Corona99]

The fish are from Golden State Discus

[Iminit]

They have some great looking discus. So I’m thinking it’s just stress. Put him in his own tank and see how he does. Remember all your fish were in different tanks a the sellers. So they’ve all been shipped and now thrown in with each other. So the pecking order starts right up and some fish being still stressed fall behind. A new start in its own tank for about a month should get it back on track. Good luck.

[Willie]

Discus are cichlids and setting up a pecking order is classic cichlid behavior. If you take out one fish, you'll see a lot of aggression as a new pecking order is developed. If you put in one fish, the same thing happen. Unlike some cichlids, discus aggression seldom lead to injury or death. The fish on the bottom of the totem pole may end up hiding behind a filter tube or sponge, but they seldom get beaten up.

With time, the fish with the short end of the stick may get stunted due to constant harassment. Because the pecking order is not rigid, having many discus will spread out the aggression over multiple fish. However, aggression is to be assumed - particularly in young (~4") discus. Having a large aquarium will also ease the level of harassment. As discus matures, aggressive behavior is less apparent except for mated pairs. Putting large discus in a smaller tank seldom causes problems with aggression.

[number1sixerfan]

I just wanted to quickly add what I've done as I've been going through the exact same thing right now. Started with 7 larger discus in a 90g tank and the aggression was just brutal to watch. Things have improved greatly, but the two smallest discus are* still being picked on and I'm still working through that now. But for weeks prior, ALL of the discus except for the two largest were extremely stressed and eating was limited. Here's what helped:

-Added 2 more discus. Have 2 more coming. This helped a bit. Puts me at overstocked, but I do large water changes every other day normally and have 3 filters on the tank.
-Turned the heat up to 88
-Added salt
-Increased water changes to daily
-Rearranged the tank MULTIPLE times. Although a pain, this was a huge help.
-taped a blanket around the tank after rearranging and kept lights off for a few days. This difference after was also a bit noticeable.

Things have improved quite a bit.. however, like I said the smallest two are still very stressed and haven't looked great. However, all of the other discus have almost completely chilled out when they were going at the entire month prior. Saw the changes in about a week. But when those two come out of their hiding spots they get chased right back. I am having a hard time deciding whether to pull them or not, as I know this stresses them even further at times + the new discus are still a bit skittish with me and I worry about making this worse by trying to catch them. Hope this helps a bit and good luck. It definitely can be stressful.

[danotaylor]

If you "turned the heat up to 80" that is potentially part of the stress issue. Discus will tolerate 80 minimally, but do best at 84+

[number1sixerfan]

If you "turned the heat up to 80" that is potentially part of the stress issue. Discus will tolerate 80 minimally, but do best at 84+

Sorry, that was a quick typo. 88-90 degrees.

[danotaylor]

:thumbsup:

[rkeane]

Similar issue as Wayne's.
In my 55 gal tank I had four 3" they were eating. After I added two 4", one of the smaller ones has stopped eating. It's been almost 2 weeks I've never seen him eat. Yet he is the aggressor... Do you suggest to QT him?