mjbarnard
Member
This is a very strange problem. I woke up this morning to find 5 dead fish and the rest gasping at the top for air. I have solved it with some immediate water changes, but do not understand it.
3 year old established tank - 125 litres. Always been overfiltered - Eheim Pro 3 2073, suitable for aquariums up to 350L. Media and filter absolutely established and water parameters have always been fine, no ammonia or nitrite ever. This is such a well established tank and filter that I couldnt believe this was a water quality issue.
25-30% water change weekly and monthly filter maintenance.
16 Rainbowfish which is well stocked, but the filtration and long term stability mean they have been absolutely fine. Up until last night they all looked healthy and active. One of the deaths was a mature blue rainbowfish who has been present in the tank from the very beginning, and always appeared healthy and active, whatever was going on.
Yesterday I did two things :
1) I did an approximate 40% water change.
2) Just before going to bed, I fed them some defrosted frozen food. Gamma blister brineshimp + spirulina. The food was from two packets, both of which were half empty, having been fed to them before. The only difference was that usually I sieve the defrosted food before feeding, but for some reason I didnt. I feed dry flake food during the week, and frozen food every Sunday.
I have recently installed a new 500L planted tank next to this one, so I have a very convenient water change system. The water empties by turning a tap from the filter outlet, where it goes directly to a drain, and there is an HMA filter plumbed in, which directly feeds the tank at the flick of a switch.
When I discovered the problem this morning I immediately took a couple of water samples and then did a 70% water change. Ammonia - 0 and Nitrites - 0. The (API) test kit must be working because ironically I did a test yesterday of the new larger tank, as I was considering moving the fish and the filter to the new tank. However there was a small amount of ammonia in the new tank (not sure why - assumed it was from plant material).
So what could have caused this?
1) Problem with the water change yesterday? Seems unlikely since changing the water this morning immediately perked all the remaining fish up, and they have appeared normal ever since. I have done a further small change this evening and they all appear fine.
2) Problem with water parameters? The tests suggest this is not the case, and the parameters have been absolutely stable for the last 3 years. No change when new fish introduced, filter maintenance etc. The tests are probably reliable, as I coincidentally checked my new tank yesterday. Unlikely due to nitrate etc, as did water change yesterday.
3) Some other disease, or toxin? No new inhabitants for several months. The only other thing I added yesterday was the frozen food. Could this be responsible?
All the fish appear much better after the water change, so I think the water and the HMA filter are good. Any thoughts? I would be interested as this is quite upsetting, and I am anxious not to allow further harm.
Thanks
Matthew
3 year old established tank - 125 litres. Always been overfiltered - Eheim Pro 3 2073, suitable for aquariums up to 350L. Media and filter absolutely established and water parameters have always been fine, no ammonia or nitrite ever. This is such a well established tank and filter that I couldnt believe this was a water quality issue.
25-30% water change weekly and monthly filter maintenance.
16 Rainbowfish which is well stocked, but the filtration and long term stability mean they have been absolutely fine. Up until last night they all looked healthy and active. One of the deaths was a mature blue rainbowfish who has been present in the tank from the very beginning, and always appeared healthy and active, whatever was going on.
Yesterday I did two things :
1) I did an approximate 40% water change.
2) Just before going to bed, I fed them some defrosted frozen food. Gamma blister brineshimp + spirulina. The food was from two packets, both of which were half empty, having been fed to them before. The only difference was that usually I sieve the defrosted food before feeding, but for some reason I didnt. I feed dry flake food during the week, and frozen food every Sunday.
I have recently installed a new 500L planted tank next to this one, so I have a very convenient water change system. The water empties by turning a tap from the filter outlet, where it goes directly to a drain, and there is an HMA filter plumbed in, which directly feeds the tank at the flick of a switch.
When I discovered the problem this morning I immediately took a couple of water samples and then did a 70% water change. Ammonia - 0 and Nitrites - 0. The (API) test kit must be working because ironically I did a test yesterday of the new larger tank, as I was considering moving the fish and the filter to the new tank. However there was a small amount of ammonia in the new tank (not sure why - assumed it was from plant material).
So what could have caused this?
1) Problem with the water change yesterday? Seems unlikely since changing the water this morning immediately perked all the remaining fish up, and they have appeared normal ever since. I have done a further small change this evening and they all appear fine.
2) Problem with water parameters? The tests suggest this is not the case, and the parameters have been absolutely stable for the last 3 years. No change when new fish introduced, filter maintenance etc. The tests are probably reliable, as I coincidentally checked my new tank yesterday. Unlikely due to nitrate etc, as did water change yesterday.
3) Some other disease, or toxin? No new inhabitants for several months. The only other thing I added yesterday was the frozen food. Could this be responsible?
All the fish appear much better after the water change, so I think the water and the HMA filter are good. Any thoughts? I would be interested as this is quite upsetting, and I am anxious not to allow further harm.
Thanks
Matthew