All Fish Dead Overnight

[Brodie Becker]

I have a 25-gallon freshwater tank. I have 4 panda mollies, 2 plecos, a cory cat, and 2 tiger nerite snails. I also have 3 live plants of some sort, although I don't know their actual species. I also have a semi-large airstone for the tank size. I am using an activated carbon filter. The tank had been set up for over a year with no problems. I recently purchased the 4 mollies, around 1.5-2 weeks ago. Last night as I went to bed, I noticed one of the mollies and a pleco dead. I removed them from the tank, and started a general medication, planning on doing a water change today. However, this morning, as far as I can tell, all of the fish but the cory cat are dead. Any ideas what could have caused this, and any recommendations on what to do? Once I have the time I will do some tests and let you know what my PH, Ammonia, Nitrates, and Nitrites are.

I also thought that it would be worth mentioning that I moved the tank around a week ago. I emptied the tank just over 75% of the way, and then refilled it around half an hour later once it was moved. The water was also a little cloudy leading up to this, but I think that that was overfeeding, as I was experimenting with how much to feed the mollies.

 

[mrsjoannh13]

If your filter media dried out It could have killed off your beneficial bacteria leading to an ammonia spike. I'm assuming you used a water conditioner to dechlorinate the water when you filled back up. Was the water also temperature controlled? Do you have a heater in the tank? Any possibility you put your hands in the tank with hand sanitizer on them?

Please do post your water parameters when you can as that could tell us a lot about what happened. Sorry for your losses.

 

[Sgooosh]

I have a 25-gallon freshwater tank. I have 4 panda mollies, 2 plecos, a cory cat, and 2 tiger nerite snails. I also have 3 live plants of some sort, although I don't know their actual species. I also have a semi-large airstone for the tank size. I am using an activated carbon filter. The tank had been set up for over a year with no problems. I recently purchased the 4 mollies, around 1.5-2 weeks ago. Last night as I went to bed, I noticed one of the mollies and a pleco dead. I removed them from the tank, and started a general medication, planning on doing a water change today. However, this morning, as far as I can tell, all of the fish but the cory cat are dead. Any ideas what could have caused this, and any recommendations on what to do? Once I have the time I will do some tests and let you know what my PH, Ammonia, Nitrates, and Nitrites are.

I also thought that it would be worth mentioning that I moved the tank around a week ago. I emptied the tank just over 75% of the way, and then refilled it around half an hour later once it was moved. The water was also a little cloudy leading up to this, but I think that that was overfeeding, as I was experimenting with how much to feed the mollies.

nononono send the data from your last test, dead fish release ammonia. first of all what species are your pleco and also panda mollies cannot live with plecos. when you change 75% you cause mini cycle cuz most of the water is recycled. this causes a small spike sometimes.

 

[Brodie Becker]

nononono send the data from your last test, dead fish release ammonia. first of all what species are your pleco and also panda mollies cannot live with plecos. when you change 75% you cause mini cycle cuz most of the water is recycled. this causes a small spike sometimes.

Why can't the mollies live with plecos?

 

[Brodie Becker]

If your filter media dried out It could have killed off your beneficial bacteria leading to an ammonia spike. I'm assuming you used a water conditioner to dechlorinate the water when you filled back up. Was the water also temperature controlled? Do you have a heater in the tank? Any possibility you put your hands in the tank with hand sanitizer on them?

Please do post your water parameters when you can as that could tell us a lot about what happened. Sorry for your losses.

Filter media stayed wet the entire time, I do have a heater, no, the only thing that could have been on my hands is a slight amount of chlorinated water, as I rinsed them prior to the change.

 

[Sgooosh]

Why can't the mollies live with plecos?

the ph is different, mollies need high, plecos dont like high

 

[Brodie Becker]

Ph: 7.5
Ammonia: .5ppm
Nitrite: Trace
Nitrate: 30ppm

 

[Brodie Becker]

Oh, it also appears as if one of the mollies is still alive as well.

 

[mrsjoannh13]

Ph: 7.5
Ammonia: .5ppm
Nitrite: Trace
Nitrate: 30ppm

It looks like it could have been ammonia poisoning if it was at that level for an extended period of time. It may boil down to a water quality issue since you had .5 ammonia, some nitrite and nitrate is a bit high (although some would argue that level is not harmful). How often have you been doing water changes and what percentage?

Can you post any recent water parameters? The ammonia from today's test may in actuality be from the dead fish.

 

[Brodie Becker]

It looks like it could have been ammonia poisoning if it was at that level for an extended period of time. It may boil down to a water quality issue since you had .5 ammonia, some nitrite and nitrate is a bit high (although some would argue that level is not harmful). How often have you been doing water changes and what percentage?

I have been doing 25% water changes about every 10 days. It has been about that long since the last one. I also usually do a 50% water change once every other month.

 

[Brodie Becker]

It looks like it could have been ammonia poisoning if it was at that level for an extended period of time. It may boil down to a water quality issue since you had .5 ammonia, some nitrite and nitrate is a bit high (although some would argue that level is not harmful). How often have you been doing water changes and what percentage?

Can you post any recent water parameters? The ammonia from today's test may in actuality be from the dead fish.

There have been dead fish in the water for several hours.

 

[Brodie Becker]

It looks like it could have been ammonia poisoning if it was at that level for an extended period of time. It may boil down to a water quality issue since you had .5 ammonia, some nitrite and nitrate is a bit high (although some would argue that level is not harmful). How often have you been doing water changes and what percentage?

Can you post any recent water parameters? The ammonia from today's test may in actuality be from the dead fish.

Last test the ammonia was around .15 ppm.

 

[Essjay]

The ammonia reading could have been caused by the dead fish - and the extra ammonia could have caused the nitrite reading.
too. But even 0.15 ppm is too high - ammonia should always be zero.

A 75% water change should not have disrupted the cycle - many of our members do weekly 75% water changes. But, as mrsjoannh13 asked, how often and how large are your usual water changes? When the usual regime is small water chnages once every few weeks, tank water becomes significantly different from tap water and a large water change can then harm the fish.


Something I do need to check with you - could any contamination have got in the water? Any aerosols sprayed in the same room, paint fumes, candles etc? And were your hands free of contamination? We have a member who lost a lot of fish from hand sanitiser poisoning. But even soap residue or hand lotion could affect the fish.

When you moved the tank, was the substrate disturbed? Another member lost fish when she disturbed the substrate by taking it out to replace it with fish in the tank.




Is carbon the only thing in the filter? No sponges or anything else? And do you change the carbon or just wash it?

 

[mcordelia]

Hmm so going with what the posters above had said, it definitely appears to be a water quality issue that caused the deaths.

Changing 75 % of the water at a time is not a problem, since the beneficial bacteria live on surfaces, not in the water.

When you changed your tank around, what did you change? Did you also do a full gravel vacuum after you stirred up stuff? I have a couple of hypotheses for what happened:

1) in moving your tank contents around, you released partially rotted matter from the substrate into the water column which fouled the tank, especially if it remained cloudy after the water change. Depending on how deeply you dug into the gravel,there could have been anaerobic pockets of decomposing matter which got released.

2) you removed enough substrate / decorations that you took out enough beneficial bacteria to cause a mini-cycle in the tank, leading to an ammonia spike.

Moving forward, it is imperative that you test your water daily, and each time your water tests above 0 for ammonia or nitrites you need to do a 50%-75% water change. Continue this until they both read 0 for three days in a row. You may also purchase bacterial starter from the pet store (Seachem stability or tetra safe start plus,etc - the product will be described as "cycle your tank" or "jump start your cycle" or similar). This will speed up the process of cycling.

Finally, to protect your fish if you are not in a position to do a water change immediately on getting a nonzero reading, you should purchase Seachem prime water conditioner, and use it instead of your preferred water conditioner. It detoxifies nitrites and ammonia for up to 48h, giving you some breathing room on water changes if you have a busy schedule.

Please keep us posted on how your fish do.

Also, regarding what @Sgooosh said about fish compatibility, it is best to match fish with the same water requirements together, ideally those that match your tap water. You can look up fish profiles on seriouslyfish.com to get their parameter information, and you can find out things like water hardness etc from your water company's report which is usually published on their website.

 

[Brodie Becker]

The ammonia reading could have been caused by the dead fish - and the extra ammonia could have caused the nitrite reading.
too. But even 0.15 ppm is too high - ammonia should always be zero.

A 75% water change should not have disrupted the cycle - many of our members do weekly 75% water changes. But, as mrsjoannh13 asked, how often and how large are your usual water changes? When the usual regime is small water chnages once every few weeks, tank water becomes significantly different from tap water and a large water change can then harm the fish.


Something I do need to check with you - could any contamination have got in the water? Any aerosols sprayed in the same room, paint fumes, candles etc? And were your hands free of contamination? We have a member who lost a lot of fish from hand sanitiser poisoning. But even soap residue or hand lotion could affect the fish.

When you moved the tank, was the substrate disturbed? Another member lost fish when she disturbed the substrate by taking it out to replace it with fish in the tank.




Is carbon the only thing in the filter? No sponges or anything else? And do you change the carbon or just wash it?

It is an activated carbon filter, with a biofilter sponge. I replace the activated carbon monthly. And yes, the substrate was disturbed.