oscar fins turning black

[disgustipated]

looking for good advice. here is the situation.

i've had my orange oscar for about a year now. he's around 20cm, and has lived by himself in his own tank all his life, up until a month ago, when i moved him to a larger tank (220l), and added 2 convicts, a jack dempsey and a pleco.

in the time he's been in the new tank i've noticed the tips of his fins turning black.. a dirty black almost like they're burnt. there doesn't appear to be much damage to his fins but the black is becoming really noticable now and doesn't seem to be getting any better. i also note that oscar has not really made friends with any of the new fish, hes still pretty aggressive to them. but the other fish still appear healthy and happy.

i've completely changed the water a few days ago and have been monitoring PH and ammonia all seem to be okay.

what causes this? how can i improve things to get rid of the black? is there medicine for this condition?

thanks.

[disgustipated]

also noticed that he doesn't dig holes in the substrate anymore, like he used to when he lived alone..

[BigBossPants]

Not sure if it helps but mine got black fin edges when he was angry

[Adrienne]

I think that the darkening off is natural and that your fish is not sick.

[myfishybuisness]

could be a sign of aggression towards the convicts (i no from expereince that they can be aggressive for there size) so maybe hes showing that hes not happy with them :an!gry

[disgustipated]

yeah gonna get rid of the convicts and the pleco i think. the tank is too small for all of them anyway.

anyone want them??

[Zayne]

disgustipated you might want to add you location, i have 3 Oscars 2 black and a white i find every once in a while one turns darker and the two (black ones) hang around at the bottom of the tank, than a few days later they act as if nothing has happened.