Tank disaster, fish dying after tank change!

CTH

EMERGENCY
Woke up today and fish are dead and dying after total tank change.
Tank
What is the water volume of the tank? 20 gal
How long has the tank been running? 18 months
Does it have a filter? Yes
Does it have a heater? Yes
What is the water temperature? 80
What is the entire stocking of this tank? (Please list all fish and inverts.). 3 snails, 2 established angels, new albino cat, established cat

Maintenance
How often do you change the water? Partial every month and 1/2 or longer
How much of the water do you change? 25%
What do you use to treat your water? pH down.
Do you vacuum the substrate or just the water? Vacuum

*Parameters - Very Important. This was a total tank change....water, gravel, filter media, decor. Everything was washed before adding to tank.
I have well water with high pH. Always add pH down to my water. Have always used my well water. Also added TopFin Redistart.

Illness & Symptoms
How long have you had this fish?
How long ago did you first notice these symptoms? Yesterday after putting fish back into tank.
In a few words, can you explain the symptoms? Fish were at top of tank. Cats were darting up very often.
Have you started any treatment for the illness? No
Was your fish physically ill or injured upon purchase? No
How has its behavior and appearance changed, if at all? Near death.

Explain your emergency situation in detail. (Please give a clear explanation of what is going on, include details from the beginning of the illness leading up to now)

when I checked fish this morning there was a cloudy scum on top of the water with some flakiness that appeared to be mostly congealed scum.
 

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Ouse

Welcome to the forum! :happy:

Doing 25% water changes only monthly is not enough I’m afraid. 30-50% weekly is advised.

The cloudy surface scum is probably a mix of microorganisms. It’s known as biofilm. Provided that this usually blooms during cycling, I must ask: did you wash all of the filter media? What did you wash it with?

Is pH down a form of tapsafe? From the name it sounds like a product that lowers pH rather than one that can be used to dechlorinate water.

A friendly reminder never to replace filter media or use tap water to clean it. Tap water (or any chlorinated water) kills the beneficial bacteria that settles on it.
 
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LanceDog

If you washed and cleaned everything and did a 100% water change, you destroyed the cycle. You are now basically starting everything over. You never need to do this sort of cleaning in a healthy tank. Weekly partial water changes and rinsing the filter media in used tank water should be all you need to do. At this point, if the fish live, you'll have to do a fish-in cycle to get everything reestablished.
 
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CTH

All decor is new. There were no soaps or cleaning fluids used. Tank change done to get rid of recurring brown alga.
 
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Mansoboy

If I understand well, you changed and cleaned all the tank at once?
In that case, a major swing on parameters and probably a cycle crash happened.
First step, do a water parameters test and check with previous numbers.

I would also add product bacteria and/or prime or similar to reduce the probably ammonia or nitrate spike.

Fish suffer A LOT on big water parameters swings, especially on PH and temperature but the others as well.
 
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Ouse

Restarting the tank completely due to brown algae is unnecessary. Brown algae can be scraped off using a razor blade. In fact it usually goes away in it’s own after a while. It’s harmless.

If you want to rinse media it’s safest to rinse it in tank water. I’d learn about fish-in cycling because what you did has undoubtedly restarted the cycle and was unnecessary.

I think the reason brown algae was spiking is because you weren’t changing the water near enough. Remember that 30-50% water changes weekly are best.

Here’s an article I wrote that’ll help you greatly!
Tips for fish-in cycling your freshwater aquarium
 
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CTH

Welcome to the forum! :happy:

Doing 25% water changes only monthly is not enough I’m afraid. 30-50% weekly is advised.

The cloudy surface scum is probably a mix of microorganisms. It’s known as biofilm. Provided that this usually blooms during cycling, I must ask: did you wash all of the filter media? What did you wash it with?

Is pH down a form of tapsafe? From the name it sounds like a product that lowers pH rather than one that can be used to dechlorinate water.

A friendly reminder never to replace filter media or use tap water to clean it. Tap water (or any chlorinated water) kills the beneficial bacteria that settles on it.


No soaps or fluids used to wash new decor or gravel.
All filter media canister filter changed and washed. New biomass and new charcoal.
Use API pH Down...sulfuric acid. Always use this for my well water....no detectable chlorine.
If I understand well, you changed and cleaned all the tank at once?
In that case, a major swing on parameters and probably a cycle crash happened.
First step, do a water parameters test and check with previous numbers.

I would also add product bacteria and/or prime or similar to reduce the probably ammonia or nitrate spike.

Fish suffer A LOT on big water parameters swings, especially on PH and temperature but the others as well.


Ammonia not a problem. Fish dead and dying in less than 12 hours. See attached picture in original post for scum.
 
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Ouse

No soaps or fluids used to wash new decor or gravel.
All filter media canister filter changed and washed. New biomass and new charcoal.
Use API pH Down...sulfuric acid. Always use this for my well water....no detectable chlorine.
Ok. So did you replace the media or just wash it in the well water?

The 100% water change likely shocked the fish. They need to adjust to this extreme change and some have died trying.
 
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CTH

Ok. So did you replace the media or just wash it in the well water?

The 100% water change likely shocked the fish. They need to adjust to this extreme change and some have died trying.
Replaced charcoal and biomass. Washed out canister and tubing. Trying to rid tank of recurring brown alga. Strictly well water.
 
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Mansoboy

Don't change all media at once, just one or partial one thing at a time. Media normally lasts for months/years and only need a gently clean every 1-2 weeks.

From now, I would do daily 20-30% water changes until cycle stabilizes again. Also use daily product bacteria, just to help with ammonia.

About the ph down product, I would not use it. My tap water is 8,4 ph and all my 3 tanks have 8-8.2 ph. I have fish with 6.5-7 ideal ph and they just thrive, they key is to keep water clean with 1 or 2 20-30% WC and stable temperature/water parameters. Fish prefers out of range stable parameters than big swings with the ideal parameters. Obviously that works with some limits, for example I would not keep discus..
 
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CTH

So starting over.....The angel fish were 2 inches in body diameter. The established cat was great.
 
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Mansoboy

Have you checked water parameters? Please could you share with us?
 
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Ouse

Don't change all media at once, just one or partial one thing at a time. Media normally lasts for months/years and only need a gently clean every 1-2 weeks.

From now, I would do daily 20-30% water changes until cycle stabilizes again. Also use daily product bacteria, just to help with ammonia.

About the ph down product, I would not use it. My tap water is 8,4 ph and all my 3 tanks have 8-8.2 ph. I have fish with 6.5-7 ideal ph and they just thrive, they key is to keep water clean with 1 or 2 20-30% WC and stable temperature/water parameters. Fish prefers out of range stable parameters than big swings with the ideal parameters. Obviously that works with some limits, for example I would not keep discus..
I wouldn’t ever replace the media at all. This will only make matters worse. There is no good reason to replace it anyway. I agree with everything else here though.
 
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CTH

Have you checked water parameters? Please could you share with us?
I’ll do tests now. Post in about 10 mins.
 
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Lvmyfsh

EMERGENCY
Woke up today and fish are dead and dying after total tank change.
Tank
What is the water volume of the tank? 20 gal
How long has the tank been running? 18 months
Does it have a filter? Yes
Does it have a heater? Yes
What is the water temperature? 80
What is the entire stocking of this tank? (Please list all fish and inverts.). 3 snails, 2 established angels, new albino cat, established cat

Maintenance
How often do you change the water? Partial every month and 1/2 or longer
How much of the water do you change? 25%
What do you use to treat your water? pH down.
Do you vacuum the substrate or just the water? Vacuum

*Parameters - Very Important. This was a total tank change....water, gravel, filter media, decor. Everything was washed before adding to tank.
I have well water with high pH. Always add pH down to my water. Have always used my well water. Also added TopFin Redistart.

Illness & Symptoms
How long have you had this fish?
How long ago did you first notice these symptoms? Yesterday after putting fish back into tank.
In a few words, can you explain the symptoms? Fish were at top of tank. Cats were darting up very often.
Have you started any treatment for the illness? No
Was your fish physically ill or injured upon purchase? No
How has its behavior and appearance changed, if at all? Near death.

Explain your emergency situation in detail. (Please give a clear explanation of what is going on, include details from the beginning of the illness leading up to now)

when I checked fish this morning there was a cloudy scum on top of the water with some flakiness that appeared to be mostly congealed scum.
I had a similar situation happened one time I basically accidentally poisoned all my face using a chemical that was supposed to rid the tank of LG I woke up the next day to only a few fish swimming around since we have had another tank handy that had healthy water in it and I simply took all the Nearly Dead Fish out and put them in a breeding net in the second tank that I had and most of them came back to life including my Angelfish Panda Cory and Twig catfish which are all supposedly sensitive to water changes get them out of that water is my best suggestion and get them into healthier water something is wrong I don't know if you can do a water test but before we adding fish you may consider going to the local pet store in having them test your water if you don't have the gear to do so yourself also did you put in stress coat it sounds like they're in complete shock I would say that stuff floating around the top was probably somehow stuck to the substrate that you added especially if it's a whole new set up couldn't be algae
Talk to text messed most of that up but i hope you get the point lol
Talk to text messed most of that up but i hope you get the point lol
Replaced charcoal and biomass. Washed out canister and tubing. Trying to rid tank of recurring brown alga. Strictly well water.
You should always use the tanks water to rinse all your filter and other stuff it kills the healthy bacteria when you use the tap so if you insist on doing a complete change which I wouldn't but if you do you gotta try to keep as much of the healthy bacteria as possible and its mostly in the substrate and filter. Did you at least use your old filter to help it cycle faster? Only rinse in tank water
 
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CTH

I’ll do tests now. Post in about 10 mins.
pH: 7.4
Ammonia: 0
Nitrate: 0
Hardness: 0
Chlorine: 0
Nitrite: 0
total alkalinity.: 300+
Any ideas about the scum floating on top.
 
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Thatguyfoot

It's just biofilm most likely most of my smaller tanks with low flow have the same film
 
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Lvmyfsh

I think its crud from the new substrate it happens as things are built so cheap now days even if we wash it lol I would skim it away with a net
 
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Ouse

pH: 7.4
Ammonia: 0
Nitrate: 0
Hardness: 0
Chlorine: 0
Nitrite: 0
total alkalinity.: 300+
I must ask: did you use a test strip or a liquid test kit? I’m lead to ask this because the results don’t tell me if the tank is cycled or not. Test strips degrade when opened and this affects the accuracy of the answers.
 
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Thatguyfoot

I must ask: did you use a test strip or a liquid test kit? I’m lead to ask this because the results don’t tell me if the tank is cycled or not. Test strips degrade when opened and this affects the accuracy of the answers.
I despise strips too many variables, Liquid kits are way too easy to rely on something as unreliable as strips. Just my two cents.
 
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Ouse

I despise strips too many variables, Liquid kits are way too easy to rely on something as unreliable as strips. Just my two cents.
I once used a strip to see if a tank had cycled and it showed no ammonia, only a little nitrite and some nitrate. I then read that strips are unreliable later on so I decided to test using a liquid kit. When I tested using the liquid kit I found the tank to be nowhere near cycled, with ammonia still being present. I’ve never used strips since, and my current liquid kit helped me cycle my 5 and 15 gallon tanks.

The accuracy of the liquid kit depends on the one you use. API Master is widely accepted but I bet there are bad kits out there. Degrading is something characteristic of test strips. I heard you can go right with strips if you’re very careful. I wouldn’t trust myself to use them before they degrade though.
 
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Thatguyfoot

I once used a strip to see if a tank had cycled and it showed no ammonia, only a little nitrite and some nitrate. I then read that strips are unreliable later on so I decided to test using a liquid kit. When I tested using the liquid kit I found the tank to be nowhere near cycled, with ammonia still being present. I’ve never used strips since, and my current liquid kit helped me cycle my 5 and 15 gallon tanks.

The accuracy of the liquid kit depends on the one you use. API Master is widely accepted but I bet there are bad kits out there. Degrading is something characteristic of test strips. I heard you can go right with strips if you’re very careful. I wouldn’t trust myself to use them before they degrade though.
I have well water and for years all I used was start right and maintained my filters now I use prime and if needed stress coat or something to calm them ... fishermen will know what g juice is that works well and but it's expensive.
 
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Lucy

Hi CTH
Welcome to FishLore!
I'm so sorry about your fish! That's devastating. I know people are asking for parameters but it would make sense that everything would be at 0 since you changed 100% of the water yesterday.

Since you have a well, any chance you have been effected by all the recent rain and flooding.
Toxins in the run off could leach into your well.

Sounds like this is a situation that maybe filled with maybes and what ifs
 
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CTH

It's just biofilm most likely most of my smaller tanks with low flow have the same film
I have an Aqueon 200 canister filter. No low flow here.
Hi CTH
Welcome to FishLore!
I'm so sorry about your fish! That's devastating. I know people are asking for parameters but it would make sense that everything would be at 0 since you changed 100% of the water yesterday.

Since you have a well, any chance you have been effected by all the recent rain and flooding.
Toxins in the run off could leach into your well.

Sounds like this is a situation that maybe filled with maybes and what ifs
The only “toxin“ in my well is sodium and chloride. So much that I have no hardness. Tests negative for ammonia and nitrates and coliforms and is 287 feet deep
I have well water and for years all I used was start right and maintained my filters now I use prime and if needed stress coat or something to calm them ... fishermen will know what g juice is that works well and but it's expensive.
I use the API chemistry kit and test strips
I must ask: did you use a test strip or a liquid test kit? I’m lead to ask this because the results don’t tell me if the tank is cycled or not. Test strips degrade when opened and this affects the accuracy of the answers.
API chemistry set
 
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Thatguyfoot

Hi CTH
Welcome to FishLore!
I'm so sorry about your fish! That's devastating. I know people are asking for parameters but it would make sense that everything would be at 0 since you changed 100% of the water yesterday.

Since you have a well, any chance you have been effected by all the recent rain and flooding.
Toxins in the run off could leach into your well.

Sounds like this is a situation that maybe filled with maybes and what ifs
I have an Aqueon 200 canister filter. No low flow here.

The only “toxin“ in my well is sodium and chloride. So much that I have no hardness. Tests negative for ammonia and nitrates and coliforms and is 287 feet deep

I use the API chemistry kit and test strips

API chemistry set
I meant as in less surface disturbance than with a HOB
 
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CTH

I meant as in less surface disturbance than with a HOB
Little roiling of the surface until water gets below the top frame of the tank
 
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Frank the Fish guy

Well water is typically very low in oxygen.

I have well water too. If I do a 100% water change directly from the tap all fish would die.

It is common for those of us with well water to need to aerate it 24 hours before using due to low oxygen. We only learn this after killing all of our fish after a 100% water change. I have been there. Sorry man. This is very common actually but often not diagnosed properly since O2 (chemical symbol for oxygen) is not part of the standard test. It should be.

Please get this test: sera oxygen-Test (O2) | sera
It works great. It shows that my well water does not have sufficient oxygen to support fish.

I fill large 50 gallon barrels and aerate my well water, then pump it to the fish room.

After 24 hours the Oxygen level is high enough for fish. But this does take the full 24 hours and good aeration.

I would only change a tank if I knew the 02 was high enough.

Don't get caught going down the rabbit hole of thinking the cycle is dying because of changing the water. Get the 02 test so you will know for sure.

This is also one reason why fish are 'shocked' from changing too much of the water. If the 02 drops the fish are very stressed. It actually has nothing to do with changing the water. Just that the 02 is too low.
 
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Thatguyfoot

Well water is typically very low in oxygen.

I have well water too. If I do a 100% water change directly from the tap all fish would die.

It is common for those of us with well water to need to aerate it 24 hours before using due to low oxygen. We only learn this after killing all of our fish after a 100% water change. I have been there. Sorry man. This is very common actually but often not diagnosed properly since O2 (chemical symbol for oxygen) is not part of the standard test. It should be.

Please get this test: sera oxygen-Test (O2) | sera
It works great. It shows that my well water does not have sufficient oxygen to support fish.

I fill large 50 gallon barrels and aerate my well water, then pump it to the fish room.

After 24 hours the Oxygen level is high enough for fish. But this does take the full 24 hours and good aeration.

I would only change a tank if I knew the 02 was high enough.

Don't get caught going down the rabbit hole of thinking the cycle is dying because of changing the water. Get the 02 test so you will know for sure.

This is also one reason why fish are 'shocked' from changing too much of the water. If the 02 drops the fish are very stressed. It actually has nothing to do with changing the water. Just that the 02 is too low.
I've never had that problem in over ten years of doing my own tanks from my well here and I've had to do 100 percent changes but that's my experience
 
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Frank the Fish guy

It depends on well depth and other factors. For example the water in a well may come from another source underground that starts with aerated water upstream. But many wells, especially wells that use ground water and are deep have low oxygen.

Here is some interesting data: https://www.researchgate.net/profil...lved+oxygen+in+groundwater+barton+springs.pdf

Note that dissolved oxygen less than 5 ppm kills fish. We see that half of the water sources at this location were below that.
 
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Thatguyfoot

It depends on well depth and other factors. For example the water in a well may come from another source underground that starts with aerated water upstream. But many wells, especially wells that use ground water and are deep have low oxygen.

Here is some interesting data: https://www.researchgate.net/profile/Mushtaq-Ahmad-27/post/Can_groundwater_have_dissolved_oxygen/attachment/59d64789c49f478072eaf131/AS:273844449808424@1442301013108/download/dissolved+oxygen+in+groundwater+barton+springs.pdf

Note that dissolved oxygen less than 5 ppm kills fish. We see that half of the water sources at this location were below that.
My well is right at 400 feet deep and the difference may just be in the fact I fill tanks straight from the hose and all the disturbance produces enough oxygen
 
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CTH

My well is right at 400 feet deep and the difference may just be in the fact I fill tanks straight from the hose and all the disturbance produces enough oxygen
This is my recent aquarium history. When I set up my 20 gallon initially about 1 1/2 years ago, I did not do anything to jump start the “cycle”. I did aerate that tank for more than 24 hours before buying the fish. About a year later I did a second new 20 gallon because the first tank had a long scratch/crack in the glass. ( I couldn’t tell which it was so I bought a new 20 gallon tank because I didn’t want a living room with 20 gallons on the floor.). Transferred the fish to a 5 gallon holding tank. Drained that scratched/cracked tank. Set up new tank. Did not aerate that new replacement tank, just transferred the fish when water temp was stable. Then I did the clean and burn on Thursday that got me in this current trouble. I’ll check out the O2 tester. (I had a 50 gallon in the ’70s with an undergravel setup and a DE canister filter (which was awesome). Never had any problems.)
 
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Thatguyfoot

I have air in two of of like 12 tanks my 125 and a 45 both I also run a higher temp than most which means less dissolved oxygen but I do it to keep ich away ...only fish death I have had has been quarantine fish from a chain store a single pictus that couldn't kick the ich ....and recently had my male jewel jump out of the tank while I was outside working
Have the fish improved any at all
 
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CTH

I have air in two of of like 12 tanks my 125 and a 45 both I also run a higher temp than most which means less dissolved oxygen but I do it to keep ich away ...only fish death I have had has been quarantine fish from a chain store a single pictus that couldn't kick the ich ....and recently had my male jewel jump out of the tank while I was outside working
Have the fish improved any at all
All four have taken that final flume ride to our septic tank. Establishing fresh tank now. Will probly buy fish on Monday.
 
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Thatguyfoot

All four have taken that final flume ride to our septic tank. Establishing fresh tank now. Will probly buy fish on Monday.
Bummer !! I hope you have a better go this round.
 
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Frank the Fish guy

Also different fish have different sensitivities to 02 drops. You can have a tank of different fish, fill it with low 02 well water, and all of one species will die, while another will survive.

As far as I understand the situation, about half of us on well water have water that is too low (<5 ppm) in 02 to support fish.

The thing is, if you aerate your water for 24 hours, it goes up to 6-8 ppm. dissolved oxygen which supports fish.

Or if you change only half of your tank water with low 02 water the fish are OK too.

The same thing also happens if your power goes out and the filter and aerator stops running. Fish will start gasping at the surface since 02 levels are higher near the surface, so they go up. But get the pumps started again and 02 returns to the water from the air.
My well is right at 400 feet deep and the difference may just be in the fact I fill tanks straight from the hose and all the disturbance produces enough oxygen

You should get the Sera 02 test so you know for sure if your well water supports fish. Usually the aeration form just filling is not enough. It takes 18-24 hours of good agitation to get the 02 dissolved into the water to support fish.

See, the thing with our well water is that the source can change over time. Basically as the water table moves up and down due to rain and drought, new water pathways emerge and the connection of water to the well can change. Sometimes drastically.
 
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Thatguyfoot

I have no doubt my water supports fish it has for ten years never any issues with oxygen
Something else that may blow your mind is I never had to add anything to the water just freshen it up every so often
 
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mattgirl

I know I am late to this situation but I have to ask. Did you acclimate your fish to the fresh water? If you didn't I have to think that is the cause of what's happening.

If you were only doing small water changes every month/month and a half your fish very gradually got acclimated to the water they were living in. By basically starting over with everything cleaned and totally new water I have to think your fish couldn't handle the vastly different parameters. This is one of the main reasons I always recommend using at least half old tank water and half fresh water when upgrading or changing tanks. By doing so the fish will not be going into drastically different water. They will just feel like they have had a 50% water change.
 
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fishnovice33

Just to clarify what other have posted that seem confusing - all that really matters is your bio media.

I have bleached bombed an a entire tank, accessories like heater and skimmer, replaced all the substrates and all the plants.

While these things have beneficial bacteria the amount is pretty irrelevant. A quality filter will have some in the other media, but if the filter is the appropriate size, the bio media should take care of everything.

Anyways I did all that and just rinsed the bio media with old tank water, replaced 100% of the water with dechlorinator, have done this many times and always stayed cycled.

Also I have found the only issue film on top of water has caused (as long as it is not coming from something non toxic or sap) messes with is agitation. It’s not the end of the world but I highly recommend a skimmer, I use them for all my tanks. Except my small 7 gallon fry tank, and a bubbler tanks care of that one.
 
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