Hi, I was out for the weekend and my sister fed my fish once a day and checked filters were running. I left the lights out. Upon my return I found that the bigger fish was apparently banged, or hurt him/herself to the point of missing scales, pretty bruised I would say.

Water parameters: (at my return) Temp 26C, pH 7.5 (slowly dropping, driftwood maybe?),Ammonia 0, Nitrites 0, Nitrates less than 10ppm.

Here's a pic showing most of Moon's bruises:


This quarrel began when the Severums began what seemed to me as mating behaviour last week. They were having some territorial issues around a driftwood that the Severums won so far. To ease things down I planted some bundles of Hornwort to create a transversal curtain in the tank.

The Oscars claimed the opposite side of the tank and I noticed some decor was out of place, I think Moon could have hurt him/herself by moving those... also I left a flat rock on that side the same day I left, I noticed that "someone" cleaned the sand that was covering most of it, but I have no proof who did that.

Should I worry about this bruises?

I have been watching over today and noticed the Green Severum got a bite in his right side pectoral fin, and Moon tail fin was also hurt, again. Aggression however seems to be fading down, in comparisson with yesterday and Friday.

Thanks
Pepe
Santo Domingo

looks fairly superficial. Just keep an eye on those areas, you don't want any fungal/bacterial infections breaking out. keeping the water in tip top condition is enough To hear a lot superficial cuts and abrasions. Just keep an eye on your Oscar, we just want to rule out any kind of skin problems.

I have also got a pair of severums that lay eggs on a regular basis, they can be territorial, however my tank is very big so I don't encounter any problems whatsoever. Tank size is a very important issue, you're more likely to have aggression problems in a small environment, rather than keeping fish in a big tank

i wouldnt worry to much about the missing scales on moon. with good water an oscar can heal up rather quickly. i would keep an eye on the aggression between the sev and your oscar although im sure that it will subside in a while when the oscar outgrow the sev its always better to be safe and watch how they interact.

As long as he dont get anymore injuries he will heal up real quick.