Agressive Discus

[Fishn']

I have a discus that acts like a male angelfish protecting his mating partner and eggs. Anyone ever owned an outlier in this docile fish group before? Suggestions? Definitively not paired up and breeding. The remaining 5 are the typical discus behavior.

40 breeder.
Excellent live plant growth and coverage.
Well fed.
84 degrees
6 discus (2 about 3.5" and remaining 4 about 2")
The aggressive one is one of the 3.5"ers.

 

[DiscusnAfricans]

Do you have a larger tank planned for the long term? 40 breeder will be small for 6 discus when they're grown. With most groups, there always seems to have a bully develop, especially if there is a size difference, so the more fish in the group, the better.

Try lowering the temp down to 81 or 82, this is generally fine for most discus, but could help a little, though not a long term solution. Maybe some dithers in the tank might help? It won't help for water quality purposes, but if the fish don't produce a large bioload, it might help spread the aggression.

 

[Becca]

Discus are aggressive. This isn't unusual at all. They are known for having a dominance hierarchy and killing off the "low man" in the ranks via persistent bullying and cumulative stress. It goes slower in large groups with lots of space, but it still happens. They might not enjoy boisterous and rambunctious tank mates, but that doesn't mean they're non-aggressive with conspecifics.

 

[Fishn']

Do you have a larger tank planned for the long term? 40 breeder will be small for 6 discus when they're grown. With most groups, there always seems to have a bully develop, especially if there is a size difference, so the more fish in the group, the better.

Try lowering the temp down to 81 or 82, this is generally fine for most discus, but could help a little, though not a long term solution. Maybe some dithers in the tank might help? It won't help for water quality purposes, but if the fish don't produce a large bioload, it might help spread the aggression.

Going in a much larger tank, 125 g, in the near future. Just growing them up a bit for now and getting the other tank established. I dropped the temp down to 81.

 

[Fishn']

Discus are aggressive. This isn't unusual at all. They are known for having a dominance hierarchy and killing off the "low man" in the ranks via persistent bullying and cumulative stress. It goes slower in large groups with lots of space, but it still happens. They might not enjoy boisterous and rambunctious tank mates, but that doesn't mean they're non-aggressive with conspecifics.

I just never saw them as this aggressive. Definitely the cichlid blood line of territory and dominance in effect.

 

[DiscusnAfricans]

Glad to hear long term plans are in the works, just had to ask. You could also try reducing the length of their light cycle, more tailored to their feeding schedule. I don't think they're as active with the lights off.

I've had the exact scenario happen that Becca described, they want to seem innocent and peaceful, but can definitely turn on their own. If one starts showing signs of damage or severe stress, you could remove them for rehabilitation, but they'll just start picking on someone else. You could easily do 12 discus when they move to a 125, just quarantine the new ones separately, and try to get some in the same size range.

 

[F8LBITE]

When dealing with discus I found having a few separate feeding cones helped getting food to the subdominant fish and keeping them well fed will keep them fat and healthy.