9 gallon tank

Question
I have recently set up a small tank and am having ongoing problems stocking it successfully.

SETUP: 34cm x 34cm wide, 28cm deep (not including gravel), 34litres, tube heater @ 27 deg.C
simple bubble filter with filter wool (ext. air pump) & small Eheim interior filter pump (with sponge)
oval rock c. 17x15x80cm, various plants c. 30% coverage
ph 7-7.5, floor: gravel, coral
Water chemistry (ammonia, nitrate/nitrite) OK.
established c. 6 weeks.  

BACKGROUND: Initially, explained to retailer that I wanted a variety of compatible fish of a quantity sustainable in this size tank.  On retailer's advice, installed 5 x 30-40cm cichlids & 1 clown loach.  I week later 2 cichlids and the loach died.  Subsequently, followed this advice from retailer:  installed bubble filter in addition to Eheim, water changes over 2 weeks with chemical additive to address ammonia and nitrite/nitrate(?) problem, added coral to naturally maintain desired pH. 1 cichlid was being bullied: swapped this for another type.  This one also bullied: returned it to the shop.  Retailer gave me an Oscar, approx. 50cm.  At this stage, tank therefore contained Oscar & 2 remaining cichlids which were the most aggressive with the others but are compatible with each other.  No signs of aggression between Oscar & cichlids, but 2 days later noticed Oscar's fins had been bitten.  After 2 more days returned 2 cichlids to shop, as it appeared that finding another fish that would be safe with them would be too difficult.  Now left with 1 solitary Oscar.  A unique and wonderful fish, but I don't like the idea of keeping it on its own.  However, from what I gather, compatibility of Oscars with other fish is problematic AND they should not be kept in a small tank.

After this comedy of errors, I have no confidence in the retailer's advice.

I would like to have as much variety and harmony possible - within the constraints of the small tank size.  From what I have read on the Internet, considering size and surface area, my tank should sustain approx. '3 inches' of fish.  The Oscar is now c. 70cm.

I would very much appreciate you advice:
1) Can I keep the Oscar with 1 or 2 other fish?
2) If I can't, could you please advise how many and what type of fish would be suitable?

Thanks

Answer
Hi Alison,
  First, your retailer is giving you very bad advice.

  Second, I think when you say "70cm" you mean "7cm" because a 70cm fish is around 2 feet long.  

  Oscars aren't compatible with pretty much anything but they are perfectly happy to live alone, in fact, they prefer it.  However, an adult oscar is 12 to 16 inches long and will need a much larger tank.  It can reach that size in
little over a year if kept properly.  While oscars do not play well with other fish, they are remarkable in terms of how they interact with people and most people that keep oscars get very attached to them.

  In a 9 gallon tank, you should not be keeping East African cichlids such as you originally tried.  These are territorial animals and 9 gallons is enough space for one of them only.  If you want cichlids in that tank, go with some of the dwarf cichlids like the West African cichlid known as the butterfly cichlid or the South American cichlid called the ram.  

-- Ron
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>