Large dark spot on oscar

[Helpmehelpme]

Hello yesterday my oscar was eating fine and everything today i woke up to feed them and only 1 ate (the one with the mark didnt) later i noticed a mark next to its mouth does anyone know what this is thanks

 

[Amboss72]

The guy could have been injured by a tank mate. The injury then can open the fish up to bacterial or fungal or viral infection. From the picture it looks like he may have sluffing of some sorts by his mouth. Observe if he’ll eat moving forward. If it’s an injury eating may be uncomfortable. It doesn’t look like any of the most common ailments oscars suffer from. If he doesn’t eat treat the fella with Erythromycin as it will treat bacterial disease, such as mouth fungus etc.

 

[Helpmehelpme]

The guy could have been injured by a tank mate. The injury then can open the fish up to bacterial or fungal or viral infection. From the picture it looks like he may have sluffing of some sorts by his mouth. Observe if he’ll eat moving forward. If it’s an injury eating may be uncomfortable. It doesn’t look like any of the most common ailments oscars suffer from. If he doesn’t eat treat the fella with Erythromycin as it will treat bacterial disease, such as mouth fungus etc.

Thank you soo much
I fed them an hour ago and it ate just just fine not as much as always but atleast it it and i heard oscars are quite moody soo maybe thats it