Fish dying in the display tank after successfully being quarantined for 4 weeks

kc10131984

Hi everyone, I was hoping you can all help me problem solve a weird situation I've been dealing over the past 3 months or so.

I have a 40 gallon display tank that is planted and well established. Maybe a lil overstocked but I keep a watchful eye on parameters and I only feed about once every other day to avoid overfeeding. I mainly use R/O water in this tank and doing a slimmed downed version of EI index dosing, and this tank gets co2 injection (so ph is around 6.5-7). Ammonio is 0-0.5 via api test, and I usually notice the spike because something has died. Nitrates are around 20.

In a separate 15 gallon tank I quarantine all future inhabitants for 4 weeks before transferring them to the main 40g display tank. The QT tank gets the same water my display tank gets (a mixture of R/O water, with a lil tap mixed in for minerals) The qt tank is bare bottom, has some plants floating around for cover, and receives no co2, so ph is usually a lil higher than my display tank...about 7-8

Over the past 3 months, I have successfully quarantined 6 cardinal tetras, probably 10 rummy nose tetras (first 6, then 4 to replace the dead ones, more on this later), a small SAE. During QT, I treat prophylactically for parasites with prazipro, and if I see ich, I treat for that too. I do not treat with any other meds unless its abundantly clear I'm dealing with bacterial or fungal infection. After 4 weeks of qt, I drain the QT tank down to about 20% water, and I slow drip water from my main display tank into the QT tank until the QT tank is about 80% full...this usually takes at least a couple hours, but I do this to ensure that the new fish are ready for any changes in ph or temp in the display tank. I net the new fish up, and pop them into the display tank. I'll usually feed the display tank inhabitants to distract them from these new fish.

Of the 6 cardinal tetras, I lost about 4 within the first couple of weeks in the display, and the remaining 2 are still alive. Out of the 10 total rummy nose tetras, I now have 2 left. I remembering transferring in 6 rummy nose tetras once, and the next day I only had 4....literally overnight they died. The remainder died slowly over a few weeks. My most recent addition, the small SAE, made it only 1 week in the display tank. I am confused af.

I never find the bodies but my tank is densely planted and I also have a good amount of snails, cories, and fish that would other wise scavenge.

My theories:

1) I have angel fish in the display tank that will eat anything that fits in her mouth. I do not transfer fish from QT that are currently smaller than the smallest successfully cohabitating occupants in the display tank that have lived with the angelfish over the past 2 years. Specifically I've successfully kept other cardinals with this same angelfish for the past 2 years, and I've never seen her attack them. I have see her absolutely crush amano shrimp and ghost shrimp though. She does seem very aware of new additions...is she picking off the new cardinals that can't hold their own? I was originally blaming my cardinal and rummy nose deaths on just bad batches, or hyper sensitivity (rummies being notoriously fragile), but I'm now starting to wonder if shes just eating my new fish, since i never find bodies. My SAE actually happily lived in my gross "farm tank" where i grow snails, plants and green water (and hardly sees water changes) before I moved her into the proper 4 week qt, and and ultimately the display tank. SAE have always been super hardy in my experience, but this one was still pretty small when it was moved in to the display tank (cardinal tetra sized)

2) is it possible that there is something bacterial or viral going on in my display tank, and that my currently inhabitants have developed some kind of immunity to it, and therefore only the new additions are dying? If this is the case, I'm thinking I should treat the entire display tank with meds.

Long story short, I have a pretty established 2 year old tank, and I've been having a heck of a time adding new fish to it. All my new additions generally breeze through quarantine and end up looking super healthy and plump by the end of 4 weeks. But then they usually disappear within a couple weeks of being released into the display tank. The fish that that have already lived in the main display tank for the past couple of years continue to do well, but any new additions seem to die quick.
 

Cherryshrimp420

I think your angel fish ate them...
 

Lucy

Hi everyone, I was hoping you can all help me problem solve a weird situation I've been dealing over the past 3 months or so.


2) is it possible that there is something bacterial or viral going on in my display tank, and that my currently inhabitants have developed some kind of immunity to it, and therefore only the new additions are dying? If this is the case, I'm thinking I should treat the entire display tank with meds.
Welcme to FishLore!
I'm sorry to hear about your fish.

This is entirely possible. A while back someone linked to an article about how when we quarantine fish we're not only protecting our existing stock from anything being brought in but also the new stock, acclimating them to our water source, giving them time to build back their immune system before adding them to your main tank where, like you said, your existing stock my be immune but the new fish are not.
I wish I had book marked that article.

Sorry, I don't have any answers other than agreeing that this is a possibility.
Good luck, I hope youget it worked out. The members have a wealth of information and are happy to help.
 

Fisch

I am sorry, it is always heartbreaking to see them getting through the starter phase only to succumb in the destination tank. I am by far no expert, but could the CO2 in the display tank play a part? Maybe the newcomers are more sensitive to this?
 

kc10131984

Thanks for the replies everyone.

I don't believe its the co2. I'm running about 30ppm of CO2 which should be extremely tolerable by all. The co2 causes my pH to drop about 1 point , so I try to account for it by slow drip acclimating the fish between the QT tank and my display tank. I think it may infact be a really hungry angel fish...sigh. Lol. Now I really wish I had the room for another tank in my house.

PXL_20210813_025605838.jpgthe suspect

I do love her tho, and she's gotten pretty big and is def the queen of the tank
 

mattgirl

Welcome to Fishlore :)

It sounds like you are doing everything perfectly to acclimate the fish to the DT. I can't think of a thing I would do differently.

If it is in fact this beautiful girl eating the newcomers is it possible to put her in a temp tank for a little while to give the new fish a chance to get comfortable in the DT? Once they do put her back in the DT. Hopefully by doing so she will leave the new fish alone.

Other than that I can't think of a way to prevent her eating them. Is it possible you aren't feeding her enough and she is just going after them because she is hungry? You may want to start feeding daily and just change more water to compensate for the higher nitrates doing so will produce.
 

kc10131984

Thank you mattgirl for your reply.

I feel like I'm the perfect example of why you should never overstock your tank. No matter how much you try, you just have to accept the golden rule to not overstock your tank. I used to feed daily, but as you said, I was getting way too much ammonia/nitrate.

I have high end biomedia jammed in every basket of my canister filter (which is actually meant for an even larger capacity tank), as well as in my hob filter (a 2nd filter I run for better overall flow since my aquarium is densely planted), and I even have bio media jammed in my co2 reactor (who knows if this is of any benefit since the co2 concentration is super high in this chamber, and thus possibly killing off any beneficial bacteria there)...and I would still sometimes see .5 ammonia simply based on the volume of poop my fish were producing daily. I simply cannot change the fact that theres only really 30 gallons of water inside my 40 gallon aquarium and that toxins will just build up quickly regardless if they are converted to nitrite/nitrate within 24-48hrs. Even with all this "excess" filtration and heavy plant load, my nitrates would be 30-40ppm before my weekly 50% water change. I cut out nitrate fertilization entirely when I was doing daily feeding.

I thought I had solved all of these ammonia/nitrate issues by cutting back my feeding to every other day. But now I've introduced a new problem to the tank in the form of a really HANGRY angel fish lolololol.

I do like your idea of taking her in and out when I introduce other fish, but I would hate to stress her more than needed, especially if its to satisfy my own desire to greedily pack more fish into my tank LOL. Also, it would require the biggest net I have to get her out...she's becoming a pretty big girl...just her body alone, without counting her dorsal fin, is almost 3 inches tall.

Thank you for your advice and also confirmation that I'm not doing something wrong in my qt process.
 

jinjerJOSH22

Keep in mind what you add to the tank most often is likely food. So if you're adding something small(in the Angels eyes), then it will likely be seen as what you always add to the tank.
I had a similar problem occur with my Three Spot Gourami, I thought since he was raised with Ember Tetras he would be fine with other smaller fish like my Purple Harlequin Rasboras, but I was wrong. I was fortunate to see what was happening and able to move them before he killed any luckily.

I hope this is your issue, as sad as it is losing fish after putting so much time and effort in, it is a lot easier to handle than potential disease that you then have to find out what it is and also treat.

Good luck and I hope all is soon well =)
 

kc10131984

Keep in mind what you add to the tank most often is likely food. So if you're adding something small(in the Angels eyes), then it will likely be seen as what you always add to the tank.
I had a similar problem occur with my Three Spot Gourami, I thought since he was raised with Ember Tetras he would be fine with other smaller fish like my Purple Harlequin Rasboras, but I was wrong. I was fortunate to see what was happening and able to move them before he killed any luckily.

I hope this is your issue, as sad as it is losing fish after putting so much time and effort in, it is a lot easier to handle than potential disease that you then have to find out what it is and also treat.

Good luck and I hope all is soon well =)
wow, I never thought of it that way. That she's psychologically conditioned to interpret additions as food. It's like Pavlov's Fish LOL. Honestly, it makes a lot of sense when you put it that way, and I always forget that fish, at least cichlids, are very intelligent. Thanks!
 

mattgirl

You are so very welcome. One thing I am wondering about. I know this thread isn't about it but I do have to wonder why you are seeing any ammonia in this tank. A fully cycled tank should not register any ammonia. If you would like we can try to get to the bottom of why you are seeing any in there.
wow, I never thought of it that way. That she's psychologically conditioned to interpret additions as food. It's like Pavlov's Fish LOL. Honestly, it makes a lot of sense when you put it that way, and I always forget that fish, at least cichlids, are very intelligent. Thanks!
If this is what's happening and it does make a lot of sense to me it will be even more important to remove her before adding more small fish. If she isn't there to see them being added then she may not see them as food.
 

Cherryshrimp420

Thank you mattgirl for your reply.

I feel like I'm the perfect example of why you should never overstock your tank. No matter how much you try, you just have to accept the golden rule to not overstock your tank. I used to feed daily, but as you said, I was getting way too much ammonia/nitrate.

I have high end biomedia jammed in every basket of my canister filter (which is actually meant for an even larger capacity tank), as well as in my hob filter (a 2nd filter I run for better overall flow since my aquarium is densely planted), and I even have bio media jammed in my co2 reactor (who knows if this is of any benefit since the co2 concentration is super high in this chamber, and thus possibly killing off any beneficial bacteria there)...and I would still sometimes see .5 ammonia simply based on the volume of poop my fish were producing daily. I simply cannot change the fact that theres only really 30 gallons of water inside my 40 gallon aquarium and that toxins will just build up quickly regardless if they are converted to nitrite/nitrate within 24-48hrs. Even with all this "excess" filtration and heavy plant load, my nitrates would be 30-40ppm before my weekly 50% water change. I cut out nitrate fertilization entirely when I was doing daily feeding.

I thought I had solved all of these ammonia/nitrate issues by cutting back my feeding to every other day. But now I've introduced a new problem to the tank in the form of a really HANGRY angel fish lolololol.

I do like your idea of taking her in and out when I introduce other fish, but I would hate to stress her more than needed, especially if its to satisfy my own desire to greedily pack more fish into my tank LOL. Also, it would require the biggest net I have to get her out...she's becoming a pretty big girl...just her body alone, without counting her dorsal fin, is almost 3 inches tall.

Thank you for your advice and also confirmation that I'm not doing something wrong in my qt process.

I hope you are adding enough re-mineralizer.... Just FYI bacteria need KH to grow so if your KH is depleted all those bio media will just be sitting there doing nothing.
 

kc10131984

You are so very welcome. One thing I am wondering about. I know this thread isn't about it but I do have to wonder why you are seeing any ammonia in this tank. A fully cycled tank should not register any ammonia. If you would like we can try to get to the bottom of why you are seeing any in there.

If this is what's happening and it does make a lot of sense to me it will be even more important to remove her before adding more small fish. If she isn't there to see them being added then she may not see them as food.
I am 100% down to investigate this further if the thread drift is permissible. I always assumed my .5 readings are either within the api test margin, or I simply had too much fish poop vs beneficial bacteria, so it just took longer for the ammonia to convert to nitrite/nitrate?

The other possibility...maybe I'm experiencing mini cycles? I currently use soft water (r/o water mixed with a lil bit of tap). In the past, I would pump in a decent amount of co2, trying to fight black beard algae. I would guess from the pale greenish yellow tone of my drop check that I was a good bit past 30ppm, and my ph would drop to 6-6.5 in the past. I don't have any buffers in the tank (like crushed coral etc) and I've read that beneficial bacteria may break down/or be inhibited when ph drops to 6, but Im a novice with regard to that area and have only skimmed on the subject. I have since dialed back my co2 (after seeing that over 30ppm did not help my bba problems) so that my co2 is at 30ppm and my ph is now more consistently around 6.5-7. Any thoughts on this?
I hope you are adding enough re-mineralizer.... Just FYI bacteria need KH to grow so if your KH is depleted all those bio media will just be sitting there doing nothing.
I've been cutting my r/o water with tap water (which is rock hard, like off the ph testing charts and kh/gh test charts) but I don't do it in a very scientific manner. I pretty much change out 15 gallons weekly, religiously, and maybe 1 of those gallons of water that goes back into the tank will be pure tap water.. All water is treated with Prime. I should prob check to make sure my gh/kh is around the desired parameter...which i believe is 3 degrees? Would love to hear more from you about this.


I think you guys are onto something. It might be multiple factors as to why im losing my fish in my display tank. Angelfish could be eating them and my new fish might just be stressed by my mini-cycles that were happening in my display tank, but not in my quarantine tank. The difference being that my QT tank does not receive co2, and thus never creeped into that 6-6.5ph range that messes with beneficial bacteria, and also the bioload is just not much in my QT tank, so ammonia is always 0. But would love to hear your thoughts on whether even a fully cycled tank will read .5 ammonia in the short term, if its overstocked.
 

Moonee

Something you can try, is puttiing new smaller fish in a breeder box for a few hours.
It works for me, Imo it makes the other fish used to it a little, Something else you can try is adding more hiding spots.
 

Cherryshrimp420

I am 100% down to investigate this further if the thread drift is permissible. I always assumed my .5 readings are either within the api test margin, or I simply had too much fish poop vs beneficial bacteria, so it just took longer for the ammonia to convert to nitrite/nitrate?

The other possibility...maybe I'm experiencing mini cycles? I currently use soft water (r/o water mixed with a lil bit of tap). In the past, I would pump in a decent amount of co2, trying to fight black beard algae. I would guess from the pale greenish yellow tone of my drop check that I was a good bit past 30ppm, and my ph would drop to 6-6.5 in the past. I don't have any buffers in the tank (like crushed coral etc) and I've read that beneficial bacteria may break down/or be inhibited when ph drops to 6, but Im a novice with regard to that area and have only skimmed on the subject. I have since dialed back my co2 (after seeing that over 30ppm did not help my bba problems) so that my co2 is at 30ppm and my ph is now more consistently around 6.5-7. Any thoughts on this?

I've been cutting my r/o water with tap water (which is rock hard, like off the ph testing charts and kh/gh test charts) but I don't do it in a very scientific manner. I pretty much change out 15 gallons weekly, religiously, and maybe 1 of those gallons of water that goes back into the tank will be pure tap water.. All water is treated with Prime. I should prob check to make sure my gh/kh is around the desired parameter...which i believe is 3 degrees? Would love to hear more from you about this.


I think you guys are onto something. It might be multiple factors as to why im losing my fish in my display tank. Angelfish could be eating them and my new fish might just be stressed by my mini-cycles that were happening in my display tank, but not in my quarantine tank. The difference being that my QT tank does not receive co2, and thus never creeped into that 6-6.5ph range that messes with beneficial bacteria, and also the bioload is just not much in my QT tank, so ammonia is always 0. But would love to hear your thoughts on whether even a fully cycled tank will read .05 ammonia in the short term, if its overstocked.

You want KH to be high, 3 degrees is pretty low. For every 1ppm of ammonia the bacteria uses 7ppm of KH. 3 dKH is about 54ppm so that will process about 8ppm of ammonia which is about 2 - 3 days for an average aquarium.

BUT that's not all, you tank will add some KH just from rocks, limestone, shells, etc so realistically your filters can go longer without replenish. But just be careful when it gets depleted because then the bio media will be doing nothing
 

mattgirl

I am 100% down to investigate this further if the thread drift is permissible. I always assumed my .5 readings are either within the api test margin, or I simply had too much fish poop vs beneficial bacteria, so it just took longer for the ammonia to convert to nitrite/nitrate?

The other possibility...maybe I'm experiencing mini cycles? I currently use soft water (r/o water mixed with a lil bit of tap). In the past, I would pump in a decent amount of co2, trying to fight black beard algae. I would guess from the pale greenish yellow tone of my drop check that I was a good bit past 30ppm, and my ph would drop to 6-6.5 in the past. I don't have any buffers in the tank (like crushed coral etc) and I've read that beneficial bacteria may break down/or be inhibited when ph drops to 6, but Im a novice with regard to that area and have only skimmed on the subject. I have since dialed back my co2 (after seeing that over 30ppm did not help my bba problems) so that my co2 is at 30ppm and my ph is now more consistently around 6.5-7. Any thoughts on this?

I've been cutting my r/o water with tap water (which is rock hard, like off the ph testing charts and kh/gh test charts) but I don't do it in a very scientific manner. I pretty much change out 15 gallons weekly, religiously, and maybe 1 of those gallons of water that goes back into the tank will be pure tap water.. All water is treated with Prime. I should prob check to make sure my gh/kh is around the desired parameter...which i believe is 3 degrees? Would love to hear more from you about this.


I think you guys are onto something. It might be multiple factors as to why im losing my fish in my display tank. Angelfish could be eating them and my new fish might just be stressed by my mini-cycles that were happening in my display tank, but not in my quarantine tank. The difference being that my QT tank does not receive co2, and thus never creeped into that 6-6.5ph range that messes with beneficial bacteria, and also the bioload is just not much in my QT tank, so ammonia is always 0. But would love to hear your thoughts on whether even a fully cycled tank will read .5 ammonia in the short term, if its overstocked.
You can go any direction you want to go on your own thread :D

I can only go by my overstocked tanks. I never see any ammonia in my tanks. Quite often folks never see a true zero reading with the API liquid test. Normally for those folks though the reading is .25 or less so seeing .5 in an established tank is concerning.

Seeing your pH dropping this low can cause problems. Unfortunately bacteria doesn't work well when the pH drops this low. You say your tap water is rock hard. Just how hard is it? I know lots of folks here have hard water. pH readings up to and over 8. I deal with soft water with crushed coral and Equilibrium so have to treat mine different than you would treat yours. I have to wonder if maybe you might be better off using your tap water. What are the actual numbers?

Maybe just changing the ratio of RO to tap water may be a better route to take. You will have to do it slowly though so your fish can slowly get acclimated to the changing parameters.
 

kc10131984

Thanks guys for the input. I need to go back and get more scientific about this. Going to evaluate the kh/gh in my display tank, in my tap watee, and in my R/O water as it leaves my RO water holding tank.

It's been a while since I've tested my tap...I just remember it being silly high... Just to give you an example, my water is so hard that my 3 stage r/o system still leaves detectable kh/gh in the water. But I'm going to go home today and get some hard numbers and will likely try to fine tune everything so that my kh/gh is closer to 5-6. As mentioned...i will likely slowly splice in more tap water to achieve this. I was trying really hard to keep rummy nose tetras which is what got me onto the soft RO water system kick about 4 months ago. Prior to that I just used tap and all was pretty well. But I kept having bad luck with rummies, so thought maybe my water was just too hard to support them. Will report back. Thx all
 

JavaMossMan

That is an amazing looking angelfish.
 

kc10131984

That is an amazing looking angelfish.
Thank you! Her name is pancake :)
 

kc10131984

Never did I think I would be testing aquarium water on a Friday night, but alas, I'm a nerd and its all pretty fun still.

So I have some good news and also confusing news. I'm happy to report my tank water is within acceptable parameters, including kh and gh.

My tank water currently reads:
PH: 7-7.2
Ammonia: .25
Nitrite 0
Nitrate 5
Kh: 7 degrees or 125ppm
Gh: 9 degrees or 161 ppm

My tank water was harder than I anticipated, since I'm using mostly R/O water..my best guess is that b/c I have a lot of seiryu stone in the tank, it's really having an effect on my water hardness.

Now the confusing part...when I tested my city tap water about half a year ago, I recall it was egregiously hard...enough to make me want to go R/O in hopes of keeping a greater variety of south American fish. I don't remember the specific numbers but I do recall my pH test was purplish, which would have been at least 8.4, and that I had to add more than 12 drops of kh/gh test solution before I could get the colors to change and thus I was literally off the kh/gh API chart which stops at 12 drops. Testing my tap water tonight, it's become clear that something has changed on a city level that makes my R/O water system seem like a waste of money almost. Tonight my city tap water tested as follows:
PH: 7.8
ammonia .25
Nitrite 0
Nitrate 5
Kh 10 degrees
Gh: 12 degrees

Still hard, but not bad enough for me to have wanted to go R/O

I also tested my R/O water and got PH 6.7, 0-.1ish for ammonia, nitrite and nitrate both 0, and kh and gh about 1-2 degrees.

So I guess I've determined that my my tap water has gotten softer for some reason, and either has a lil ammonia in it or it's within the range of error. Given that my state is in a drought (California) I will likely dial back the R/O water (since it takes 4 gallons to make 1 gallon of r/o) and take advantage of my city tap for the time being. I guess I also don't have to worry too much about not having enough of a buffer against pH crashes/cycle crashes due to co2. So....I think Pancake is still the likely cause my fish deaths.

Here's a full tank shot, just because. Have a great weekend everyone
 

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Cherryshrimp420

Yeah unfortunately not every city has stable water. Your local water report may tell you how much the parameters fluctuate. Nice tank as well :)
 

DoubleDutch

I seriously expect the difference in Ph and possible swings (use of CO2 and RO water) is culprit and seriously doubt it is the (beautiful) angel.

Both fish (cardinals / rummynoses) are notorious for this (also Ph difference lfs / keeper)

I great.complinent about the way of QTing and putting display water in there to make them adapt. Never seen this great way !!!! Only think you had the wrong fishspecies to cope with the difference . Maybe it is an idea to do earlier waterchanges in the QT-tank with water from the display tank.
 

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