Should i be using the geo and the salts or not?
Well the geo liquid wont hurt but the salt would have more benifit with helping him by helping with the stress from the water quality.
Salt needs to be used with caution too,, Id suggest reading this link
http://www.worldcichlids.com/faqs/salt.htmlAlso take any advice from a LFS with a grain of salt,, your best off getting advice from forums like this.
what is the best food for him? live or pellets.
The best staple diet is pellets or the beefheart recipe
http://www.worldcichlids.com/diseases/Adamhith.html#Anchor-Ingredient-56874never feed live fish, expecially goldfish as they lack any sort of nutritional value and goldfish in particular contain a enzeme that robs the oscar of neccessary vitamin intake.
Other foods can be meal worms,grasshoppers, other bugs but at this stage I would just stick to pellets for a little while untill the tank size is sorted out.
i was told his tank would do him for 6-12 months,
That sounds a LFS talking there,, oscars grow at a very fast rate and create a mess when eating. You then also have to subject the oscar to another stressfull tank move.
Anyway the best advice to get him hopefully back on track is to those daily 10% water changes and once his appetite returns please feed sparingly to start then considering his size ATM feed twice a day and only what he can physically eat in 20 seconds..
Thats cool about making mistakes and if you do lose this one (hopefully you wont) just wait untill you can get that bigger tank and use the 60 litre for something else(goldfish are colourfull but boring with no personality lol )