Hi - I had a 4 month old beautiful albino Oscar, who loved to cuddle and hand feed. Her tank sprung a leak, looking to upgrade for when she grew bigger, bought a 160litre enclosed, complete tank w/canister filtration (ammonia noodles, bacteria balls, foam - all rinsed) using the water from the old 50litre tank, and gravel, added new gravel (washed), ph balanced, added the Oscar and armoured bristle nosed catfish (still living). The oscar fed straight away and seemed fine. within 24 hours the Oscar was swimming vertically nose up, then nose down, then on her side and died a total of 48 hours later. I took sample of water to shop where I bought her and tank, all water came up fine with just a tiny shade of green in ammonia - but it looked yellow to me. Advised to put platy in tank after partial change, did so and platy survived, same with the catfish. Put in new baby oscar, within a couple of hours was hiding, then swimming on side, then lying on side and took 4 days to die.....Only thing new is plastic ornament - bought from fish shop, added aerator in case O2 was problem. Catfish and platy still going - no signs of disease on any fish...help...

hey there and welcome.
If i read you took a new filter and rinced it, it seems like the tank was not cycled.
This will result in ammonia and nitrites in your water, wich will be deadly if concentrated enough.
Cycling a tank takes 6 weeks. please read the section on cycling on the top of the homepage, that will explain the cycling proces.
Oscars should be introduced in a fully cycled tank, for they are very sensitive to toxins from their own poo.
You should get a liquid master test set so you can test for yourself what the waterconditions are, for LFS often say fine or good, whereas we differ in opinion here on the forum.
Catfish and platys can survive harsh conditions, compared to oscars,btw...

Hi Noddy - thanks very much - I'll do that, leave things be with the fish that are surviving and then give it a go....I had to replace the tank as the old one was splitting, leaving a puddle on the floor. The fish shop folk said as long as I used the water and gravel etc from the existing tank everything would be ok. Not sure what I could have done in the circumstances....but it cost me my lovely Oscar. They've also sold me a tank that is 30"x18"x18"saying that will be big enough for one oscar - holds 160litres, but this site tells me otherwise...

Hi Barnett....

Loads and loads of info on a 'tank setup' which is found at the top of the home page. A 30"x18"x18" is not big enough for your Oscar, it works out at just 35gallons. One Oscar requires 55 each roughly but read all the articles at the top of the home page Bar and you will see.

On the home page on the lefthand side you will 'Tank calculator' this was where I found out ur gallonage. If there is such a word lolol