mixing fish

Question
hey!, i have a tiger oscar(2 and 1/2 inch) and a yellow chidlid (inch) and a electric blue chidlid (2 inches) together in a 2 foot tank, i did have a red gourami in there for about 3 weeks but it died. i just got the yellow to replace him... i was wondering if the oscar and electric blue could have killed the gourami and i was wanting to kow if they might attack the yellow chidlid? i am very soon(as soon as i can find a place to set it up) upgrading of course to a 3 or 4 foot tank, will this stop this sort of thing happening again?
also can i put another oscar about the same size but albino in with the three? or once i upgrade?
i am a little worried im spending money on these fish only for them to eat eachother!!! thanks in advance.


Answer
Hello,
An Oscar needs a 60 gallon tank all to himself, and two you must double this..120 gallon tank.  It is not good to mix Oscars with African Cichlids since they do not have the same needs.  The African Cichlids need hard alkaline water, the Oscar needs acidic to neutral water.  African Cichlids are more aggressive, and territorial, and should not be mixed with South American Cichlids.
For an Oscar to live well, be healthy, and happy, he must have 60 gallons of water all to himself.  If you do not follow this rule, you will have an Oscar with a stunted growth, who will get sick, and there will be no cure to help him.  Vendors do not tell you this when you buy them, and they never take an Oscar back which has outgrown a tank.  They are there to make a buck, and couldn't care less.  An Oscar is a wonderful fish to have, and is very clever.  We do get very attached to them which is why I am writing this down for you.  
An Oscar should have a varied diet.  Here is a list of foods an Oscar should have:

Crickets bought at you pet store
Worms bought at the bait store, and cleaned.  To clean the worms put them in oats for a week or so.
Minnows bought at your bait store.  Buy the regular kind.
Veggies such as peas, green beans, carrots, spinach, boston lettuce, and broccoli.  I buy most of my veggies at the market in the frozen section.  I take out the amount I want to feed my Oscar, blanch them, let them cool, and feed them to him.
Mangoes, and bananas,  now and then.  No citrus fruit.
A good quality flake
Pellets that are best previously soaked
Frozen fish that come from rivers, and lakes.  (Never feed salt water fish to an Oscar)
Never feed him feeder fish.  Feeder fish are usually full of disease, and have no nutritional value.

Do your water changes every week, and check for ammonia, and nitrites often.  Oscars are messy, and need clean water, good chemistry, which means weekly water changes.
I hope this helps you understand the Oscar a little better.
Lynda