+2 it's food stuck somewhere and you can't find it. incredibly nasty smell. and very hard to find.
I have the same problem. 4 ft tank with convicts. New set up. I tested the water at the lfs and it was nearly zero ammonia, no nitrate, small amount nitrate. Ph 7.4. I have a lot of plants in there, nothing rotting, no dead fish. About 11 fish. Total length of fish is 44cm in a 220 litre tank. 29C. Guy at the fish shop said it was algae, even though not visible. Recommended algae killer. A liquid one by Apia or a block one for ponds. I tried the liquid one as I had it, from a goldfish tank problem ages ago, that was in a sonetimessunny corner. Luckily I only put 5ml in which is a bit more than half dose. All fish went still and sleepy. I panicked severely. They recovered enough after a while that I could sleep. This morning all smell is gone. The smell was not a pleasant earthy smell. It was polluting the house. The fish are not quite back to normal chasings but active enough. If you use this Apia product use way less than the recommended dose. I had done so many water changes, the fish were happy, but it stunk. View attachment 1312166
Thank you. The lids are all scrubbed, but as I said it’s a new set up. What do you mean by covered them? Do you mean I fixed it.You could possibly covered them. Also check the rim of the aquarium for food stuck there.
Maybe, but with all my paranoid water changes , syphoning I thought that would have been removed. I did two 30 sec feeds or one a day.Spell check sorry
It should have been possibly overfed them.