I set my tank 2 years ago. In 450 liters aquarium lived 4 oscars (about 28 centimeters length) and 2 red parrots (about 15 cm length) and some catfish. Outside Filter JBL 500 1200 liter/hour, inside mechanicel filter 800liter/hour.; temp.+25C. Parameters are good: Ammonia= 0 ; Nitrite= 0 ; Nitrate=10. I do water changes every 7-10 days about 15-20%.

2 mounth ago 1 my oscar started gasping and stoped eating (They eat Hikari food). Bacame sad and apathetic to everything. Abnormally strong gill activity was too. First of all I used medicament JBL Furinol - nothing has hapend, then JBL Gyrodactol against Gill warms- NOTHING! This state continue 3 weeks untill my oscar died. I thought that it was some very difficult to diagnose disease. But after 2 weeks my second oscar became the same condition- started breathing heavily and stoped eating. 10 days ago I did salt procedure 3 grams in to 1 liter water. After 2 days in salt water fish became very bad. Was gasping and lying on the ground. Then I changed the 40 % of water and put un-bacterial medicament called " Supplin ". Then I saw a little miracle MY OSCAR ate a little. But today is the 5 day that he is swim aapathetic with strong gill activity and don't eat any thing. I DON'T KNOW WHAT TO DO? WHAT medicine TO USE? PLEASE HELP!

Thanks, Oskaras

its sound like ur over stocked for one. and when u do the stuff in the tank to u pull ur carbo from ur filter out?

After first fish death I put carbon into the filter for some days to clean water from stuff and pull it out after a week.