Short Answer - Yes and No, most oscars will get more aggressive as they age, however each oscar is different and some of them are perfectly fine with other fish in the tank. More so if the other fish were already there when they were growing up. I even had one which was perfectly fine with a goldfish in the tank.... . If your oscar does get more aggressive, there are ways to control that aggression. Rocks, driftwood and other barriers could be used to provide 'natural' barriers to oscars enabling them to carve out a territory for themselves.
Will an Oscar get more aggressive as it ages?
- Thread starter jamntoast
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I believe its another case of tank size imo, oscars with plenty of room I haven't seen seek out fights; as opposed to say a dovii which will find things to murder, even when it has ample space lol
I have seen the opposite in an 8 foot long tank with 2 different oscars at 2 different times with 2 different bullies. When smaller they were getting harassed by a particular fish. Once the oscars got as big as the bully, they chased and bit the bully (2 different bullies for 2 different oscars) every chance they saw them.
So I've noticed, now that everyone has been together for a few days, that the o is definitely the boss now. The o and the uaru seem fairly indifferent to each other but the geos won't even stay near the oscar. I've caught it giving them a little chase every now and then but no one is showing any injuries or marks from fighting, so I don't think the o has been too aggressive. I wonder if it's a instinct thing and they recognize the Oscar as a predator or something. Even my biggest geo who won't back down to uaru and who I previously thought had a pretty bad demeanor just runs away every time the o comes near. There is noticeably less squabbles between the geos now though. That's good I guess
I got my first Oscar a couple week back.. he is less than 3".. Up until this morning he was in the tank with 3 Pearsei between 6 and 9" in size and 3 chocolates same size as the Oscar.
The Oscar did not hesitate to nip at the pearsei when it thought they were trying to butt in line for food ahead of him..
Moved the pearsei out to a bigger tank this morning, and now the Oscar seems sullen.. Have to get him some target fish mebbe..
The Oscar did not hesitate to nip at the pearsei when it thought they were trying to butt in line for food ahead of him..
Moved the pearsei out to a bigger tank this morning, and now the Oscar seems sullen.. Have to get him some target fish mebbe..
Oscars are big pouters, move a rock and they get depressed. I would give it a day or 2.
From my experience, oscars peek their aggression at 8" attitude starts at 6" but as they get old and fat, the become more timid and lazy but the attitude and personality never fades.
I have a pile of good sized agates in brutus' tank , when I move them back into a pile he will hunger strike for a couple days minimum.
