Oscar attacked in first real signs of aggression in tank

[Lucifer0411]

I've had this Central/South American tank running for about 15 months - all grow outs so most only about half way there.
Hardly seen any aggression the whole time. Still haven't actually seen much but then overnight my 6-7 inch oscar pictured has a big chunk out of his tail.

The tank is 10ft long, 335G.
I'm thinking its either the other oscar - a slightly smaller one I introduced about 6 weeks ago (but was the dominant one in his group), or one of the red devils, or jags, or salvini or Vieja possibly. They are all around the same size bar one of the red devils and the Vieja Melanura but they are still pretty cruisy at the minute.

Well clearly one fish isn't.

I think I'm inclined to see how it pans out over the next few days or so. If nothing else occurs I'll let it be. Anything else I'll pull him out and put into another tank.

 

[SAGuy]

IMHO, the poor oscar is out of place in that CA tank.

This seems to be the wisest course of action:

... I'll pull him out and put into another tank.

 

[Lucifer0411]

IMHO, the poor oscar is out of place in that CA tank.

This seems to be the wisest course of action:

Yes I've decided I will re-allocate/reimagine my 5ft 150G tank to a SA Cichlid tank (currently a semi planted tank but I guess the oscars will take care of that over time lol.). Bit of prep to do and removing some smaller fish first though.

I'll remove the two oscars out of that tank - both around the same size and I think also the 2 Jack Dempseys which are smaller. I've had them for over a year and they are still only around 4-5 inches and don't seem to get much of a go with the faster growing more aggressive fish. They seem very healthy though and in perfect form. I think they will also do better in another tank. Then the few Ellioti I might also move to the 150 (to join some other ellioti in that tank already). That will complete the 150 then, no real aggressive fish and also clear out the 330G some which will then leave mostly CA cichlids and the green terror in there. I think the 5 or 6 convicts in there should be ok though.

On the plus side his tail is already growing back fast.

 

[SAGuy]

If you want to keep this many different fish, it sounds like you need three tanks to be honest.

 

[duanes]

If you want to keep this many different fish, it sounds like you need three tanks to be honest.

Agree with the above.
Oscars really don't belong in a tank with Central Americans, aside from aggression issues, the softer lower ph water parameters preferred by Oscars, are very different than the hard, high pH waters Central Americans come from.
And as suggested by the comment about at least 3 tanks.
Aggressive Central Americans like managuense,red devils and some Vieja, are usually too much for less aggressive cichlids like JDs.
Even in nature, when JDs share habitat with more aggressive types, they don't do well.
In the first video below where JDs share habitat, they are quite torn up, and there population is low.
027 zps4b102ffd
Yet in habitat where they are the alpha, or only cichlid, they do much better.
Eden2

 

[Lucifer0411]

Agree with the above.
Oscars really don't belong in a tank with Central Americans, aside from aggression issues, the softer lower ph water parameters preferred by Oscars, are very different than the hard, high pH waters Central Americans come from.
And as suggested by the comment about at least 3 tanks.
Aggressive Central Americans like managuense,red devils and some Vieja, are usually too much for less aggressive cichlids like JDs.
Even in nature, when JDs share habitat with more aggressive types, they don't do well.
In the first video below where JDs share habitat, they are quite torn up, and there population is low.
027 zps4b102ffd
Yet in habitat where they are the alpha, or only cichlid, they do much better.
Eden2

I think my initial solution will be ok for the start. The idea more medium term is all the Ellioti will go off to another tank together or I move them on. I do have another 75G for them IF i keep them...but you can't keep them all can you.

SO the large tank will only have the larger CA's primarily, the 150G will have 2 oscars & 2 JD's, maybe a few convicts from the main tank later on...or maybe not. So apart from bristlenose etc there will eventually only be the 4 main fish in the 150G which I think should work OK....and with working on adding terrestrial plants to that tank, it should be maintained with pretty low levels of nitrate. I'm certainly a big fan of low nitrate low maintenance tanks. I think I can even achieve that in the big tank with terrestrial plants right along the top. We'll see.