6 fish died today, huge spike in ammonia and nitrites

Hi everyone. Have a bit of an emergency. I have a 45 gallon aquarium that is cycled and established for 5 years. It has been VERY stable up to now. I performed my usual 25% water change last Saturday but really focused on removing gravel waste. I also added the usual dechlorinator to the tank before adding in new water. Come Tuesday, my wife (who feeds them every morning) advised me the fish are all bunched together on one side. I observed the fish looking like they were desperately trying to escape. Today, the fish were dying one by one by the hour. I tested the water (using a very old API kit) and ammonia was at 1ppm, nitrites 20-30 ppm and nitrates 0. Now, this could be completely wrong since the kit is 4 years old. I went out to the local pet store and purchased a 'stick on' ammonia reader but it shows 0 ammonia. I don't have much faith it is very accurate but wanted something to measure ammonia levels since they did not have the API kit available. I will also mention I introduced 5 neon tetras from Petsmart 3 weeks ago and all seemed fine up to today. I'm left wondering if I may have introduced a disease to the community. However, it seems strange to me that 6 fish died in a 12 hour timespan. This leads me to believe the water parameters are out of whack due to the cycling being stunted.


Edit: I have performed a 50% water change and added Seachum Prime dosage, with hope it will 'jump start' the cycle if it's out of whack. I plan on doing another change tomorrow and daily until I can find an API kit to test the water. Please help!

45 gallon stocked with:

7 neon tetras - now down to 2

4 rasporas - now down to 3

2 albino plecos (1 appears to be very lethargic)

several live plants - I forget name of plants

Temperature - Steady 74 degrees F

Penn Plax 50 gallon internal filter

Looks like something is casuing an ammonia spike for sure based on the test. But there's no nitrites (contrary to what you said in the OP) showing so I think the cycle is still working fine. There's maybe 20+ nitrates showing and zero nitrites. So, ammonia could be due to something that's dead in the tank or overfeeding.

Ram419 said:

Looks like something is casuing an ammonia spike for sure based on the test. But there's no nitrites (contrary to what you said in the OP) showing so I think the cycle is still working fine. There's maybe 20+ nitrates showing and zero nitrites. So, ammonia could be due to something that's dead in the tank or overfeeding.

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My bad, totally confused the two! Several fish have died in the past 12 hours but I've been removing them as soon as possible. Should I continue doing 50% water changes daily (or less) I didn't see any more dead fish but am left wondering if one maybe got stuck in the filter and I miscounted.

As I understand 'cycling', ammonia->nitrites->nitrates.How can ammonia and nitrates be so high yet nitrites are at zero?

Definitely suggest water changes until you reduce ammonio to zero. 50% daily should be fine without causing any issues.

What's the pH of the water?

Pictures of the dead and remaining live fish so we can check them for disease?

It's unlikely the neons you got 3 weeks ago brought a disease in. They might have brought in white spot. That shows up as small white dots on the fish's body and fins. But most other diseases would kill a lot quicker.

What did you do to the aquarium yesterday?
Did you have visitors yesterday?
Did anyone spray or smoke around the aquarium yesterday?

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If you lose fish suddenly/ unexpectedly, do the following:
Test the water for ammonia, nitrite, nitrate and pH (you have done that, except pH).

Do a 75% water change and gravel clean the substrate every day until you know why they died. The water changes and gravel cleaning will dilute chemicals, poisons and disease pathogens and buy you time to try and figure out what is going on.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

Get pictures of the sick, dying and live fish so we can check them for disease.

Colin_T said:

What's the pH of the water?

Pictures of the dead and remaining live fish so we can check them for disease?

It's unlikely the neons you got 3 weeks ago brought a disease in. They might have brought in white spot. That shows up as small white dots on the fish's body and fins. But most other diseases would kill a lot quicker.

What did you do to the aquarium yesterday?
Did you have visitors yesterday?
Did anyone spray or smoke around the aquarium yesterday?

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If you lose fish suddenly/ unexpectedly, do the following:
Test the water for ammonia, nitrite, nitrate and pH (you have done that, except pH).

Do a 75% water change and gravel clean the substrate every day until you know why they died. The water changes and gravel cleaning will dilute chemicals, poisons and disease pathogens and buy you time to try and figure out what is going on.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

Get pictures of the sick, dying and live fish so we can check them for disease.

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Hi Colin,

It's been a long time since I've logged on, but your insight has been invaluable in the past when I was starting up my 45 gallon!

Yesterday changed out roughly 60% of the water, thoroughly vacuumed the gravel and added Seachem 'Prime' and the remaining Seachem 'Stability' I had.
No visitors
No smokers inside the house

To my astonishment, I didn't lose any more fish overnight. Honestly, I was expecting dead bodies everywhere when I woke up this morning =( The fish 'seem' to be acting a bit more normal, they at least aren't looking like they're having a panic attack or halfway to the grave. However, it's concerning how they all seem to be grouping together on the filter side - I never see all of neon tetras, rasporas and whitecloud danios 'schooling' together. I was unable to find an API test kit (the pictures I posted is from an API kit that is 4 years old, so I don't trust the results) but I purchased a 'stick on' ammonia tester. As of this morning, it shows as '0'.

I plan on changing out 20% of the water today and adding in 'Prime' to treat the tap water. I am still a novice, but based on experience, it sometimes is best to 'ride out the storm' rather than just aimlessly adding treatments, hoping one works. I'll continue changing out the water daily for the next week, adding 'Prime' to the tap and hopefully the cycle normalizes sooner than later.

I am a bit confused though how the ammonia and nitrates are high, yet nitrites are at '0'? If I recall correctly, ammonia is converted to nitrites and then nitrites are converted into nitrates. Again, this was tested with a kit that is 4 years old...it's all I had yesterday.

I've included some pictures, but I apologize for the quality. The Raspboras, White Cloud danios and Albino pleco's look healthy to me. However, the pleco (which was impossible to photograph and neons are not looking good at all - they appear to be wasting away =(

Could it be you "unearthed" something during your thorough cleaning?

How old was the stability that you used the last of? Could it have expired?
Nitrate will remain in a tank until it is removed by a water change so it isn't unusual to see it alongside ammonia.
Testing after a mass die-off could show an ammonia spike that is later converted to nitrite/nitrate as the beneficial bacteria multiply enough to deal with it.

outofwater said:

Could it be you "unearthed" something during your thorough cleaning?

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Looking at the pictures, it doesnt look like a thorough cleaning. LOL. Still a lot of algae but I was able to vacuum quite a bit of debris.

Maybe a dead plant leaf or something? I definitely didnt see any dead fish being vacuumed and I keep count if one is missing. I've been using the same water source (city tap) for years. Perhaps the PH drastically changed? I won't be sure until I can test. I did notice the other day, my wife who feeds the fish every morning was putting WAY too much food in the tank. I advised her the fish need 1/4 that amount and she scolded me, saying "I've been feeding them this amount for years". Thankfully, it's only once/day but I may need to take over the feedings. LOL.

Stability was a few years old but I added after the crash. It was maybe 1 capful (enough for 10 gallons) For the 'Prime', should I add the full amount for 45 gallons, or just the water I replace each water change?

Don't waste your time with small 20% water changes. If there's something bad in the water, do a big (75%) water change to dilute whatever it is.

If you do a 20% water change each week you leave behind 80% of the bad stuff in the water.
If you do a 50% water change each week you leave behind 50% of the bad stuff in the water.
If you do a 75% water change each week you leave behind 25% of the bad stuff in the water.

Colin_T said:

Don't waste your time with small 20% water changes. If there's something bad in the water, do a big (75%) water change to dilute whatever it is.

If you do a 20% water change each week you leave behind 80% of the bad stuff in the water.
If you do a 50% water change each week you leave behind 50% of the bad stuff in the water.
If you do a 75% water change each week you leave behind 25% of the bad stuff in the water.

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After 3 major water changes in 2 days, retested and results look much better for now. Fish seem to be acting normal again but lost all of my neons...I'm hoping these aren't false results from the 'Prime' I added with the last water change from 24 hours ago. Plan on another major water change 50% tomorrow.

Ammonia - 0 - .25ppm
Nitrites - 0 ppm
Nitrates - 10-20 ppm

steelo said:

For the 'Prime', should I add the full amount for 45 gallons, or just the water I replace each water change?

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I've never used Prime nor stability but for the API water conditioner I only add enough for the new water, never been a problem and saves money. The biggest advantage though is that there are less additives in the tank so the fish have purer water.

Naughts said:

I've never used Prime nor stability but for the API water conditioner I only add enough for the new water, never been a problem and saves money. The biggest advantage though is that there are less additives in the tank so the fish have purer water.

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The only chemical I add is Tetra brand dechlorinator for water changes as the aquarium has been very stable for 5 years. I do add in liquid plant supplement 1x per week. About 2 weeks ago, I removed the entire filter and scrubbed the casing with hydrogen peroxide to get rid of some nasty bearded algae (and rinsed the element in tap water) I know rinsing the sponge element in tap water is a 'no-no' but I've never had issues before this week. I did very thoroughly rinse off the hydrogen peroxide and the outside of the filter. Just to play it safe, in the future, I will clean the sponge in aquarium water only.

In this case where the ammonia level spiked for no apparent reason, I used Prime and Stability, along with 50% water changes with hopes it would jump start the beneficial bacteria.

I appreciate the help and insight from everybody! I performed another 50% change and vacuumed up more debris. After 2 days of fasting, I gave the remaining fish a pinch of flakes. So far, no more casualties and the fish appear calm again, albeit heavily favoring the filter side. I hope to restock in a few weeks when I'm confident it is stable again, but have given up on neons (which breaks my heart because they are one of my favorites) I'll probably get 4 rasporas, bringing the total back up to 6. I have 6 Whitecloud danios and those are tough little fish! No casualties, 2 siamese algae eaters and a pleco survived. Does anybody have suggestions on a hardy fish to replace the neons? I was thinking about maybe 4-6 zebra danios? It's a 45 gallon and I'm trying to leave some headroom and not overstock.

Readings this morning after water change:

Ammonia - 0 - .25 (there is a tinge of green but very close to 0)
Nitrites - 0
Nitrates 10
Temperature - 72 degrees F

steelo said:

About 2 weeks ago, I removed the entire filter and scrubbed the casing with hydrogen peroxide to get rid of some nasty bearded algae (and rinsed the element in tap water) I know rinsing the sponge element in tap water is a 'no-no' but I've never had issues before this week.

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I've read that hydrogen peroxide can crash a cycle but have no experience. What strength was the solution?
Once tanks are well established (1+year), using tap water on the filter media doesn't disrupt the cycle so there will be something else that caused the ammonia.
It's promising that your test results are staying safe so keep up what you are doing.

Why are you giving up on neons if they are your favourite? If you revisit @Colin_T s questions he may say that they are viable? Knowing the pH, GH and tank dimensions will help for future fish suggestions.