Unknown Diseases? Please help

Question
Hi chloe,
 I was hopeing you could help me. I have a few questions.

1.  I recently brought some Mollies for my tank last week and today I relised that two of them had what appeared to be dark black eyes, the othere ones on them are fine but they are acting wierd and I'm afraid that something seriously is wrong.  Please Help..

2.  My partner Has a Oscar in his tank along with some other fishes and for the last 6 months or so the Oscar seemed to have what to look like 'hole in the head' but he's done every thing that the fish shops told him to do, the oscar seem healthy though and doesnt bother any other fish *beside eat every thing which its well known for*. But I was wondering if it could have some other problem similar to what looks like the holes in the head.  If it is hole in the head what do you surgest as he's tried feeding worms, changed his diet as well as putted stress tablets in the tank as the pet shops told him to do.  

Cheers,
Chantelle

Answer
Hi Chantelle,
The black eye sounds like a water quality problem such as high ammonia levels. Did you cycle the tank before adding the fish?
Oscar's are very prone to hole in the head disease. Unfortunatly it is very difficult to treat and only a few things can be done. Try adding some epsom salt to see if this helps. It can be caused by poor water quality so do a large water change and syphon the substrate.

Hope this helps
Chloe.