Multiple fish death with no cause?

I’ve got a planted 60 gal community tank that for the last month has been losing fish randomly and more so within the last week or two. It has serpae tetra, neon tetra, 3 types of rainbows, oto, a bristlenose pleco, and bronze cory.

I first lost an oto, 6 neons, and 7 new orange Venezuelan cory. The oto and neons were older fish. The oto over two years the neons even older. So I assumed that they were dying one by one of old age. The cory I got were from aquahuna and were very small so I assumed they just stressed out and were weak and couldn’t handle it. Got a refund and didn’t think any more about it. Out of concern though, I chose to rescape the tank last week just in case there was something dead caught somewhere causing issues because I only found a few bodies. I believed the rest to be eaten but better safe than sorry and the tank had been running for about a year anyway.

Then, I got 7 new neons to replace the old ones and give the remaining neon a school. They were healthy and active… and then started disappearing. Went from 8 neon to 4 to 3 to none within a few days. Even the old one was gone and I only found maybe 3 corpses. Then a serpae tetra died. And now I had a turquoise rainbow die this morning and another with a white patch on its side that I assumed was a scratch. I now have him in a 2 gal bucket with methalyne blue, paraguard, and a dose of erythromycin. He’s the first to have a sign of anything physical wrong. No one else has nor their corpses.

Parameters were checked yesterday. 0, 0, 30. Temp is just below 80F/26.7C. Water changes are weekly or every other week with a filter clean (I rinse in tank water) every month. Ph is 7.4. Feeding is every other day with omega one flakes and omega one sinking pellets for Cory with an occasional algae wafer for pleco. Only thing that’s changed the last month other than the rescape is I went from Thrive + to Thrive C for plant fertilizer.

And unfortunately I do not have a quarantine tank. My options are limited when I live with my parents who want me to be rid of the tanks anyway. So all new fish are floated with tank water added every 15 min for an hour. I make sure they have no physical signs of issues and then closely monitor them once they are in the tank. All new fish were colored up quickly, active, and ate for days after they were added. I saw no issues until they went missing about 5-7 days later

pictures of the tank are attached as well as the dead turquoise from this morning and the one I have separated for their seeming injury.

 

Not sure if this helps, but I use a 10 and 15 gallon sterilite storage tub/tote for quarantine. When not in use I pack up my fish stuff in them. When I need them I put everything into a reusable grocery bag and use the tub. Very cheap and easy to get and only temporarily takes up a little room, not sure if that's something you could fit in your bedroom.

The lack of quarantine could potentially bring in things you'd not want there. The cause for this I don't really know, but hopefully someone else will have a better idea of what's happening.

You want to keep nitrates under 20 ppm at all times with fresh water fish. I'm not sure if there's any exceptions for certain species. By the time you do a water change you want it no higher than 20 and bring it down to what you need it to be before it builds up again.

I would do extra water changes to get this nitrates down in the mean time.

 

I’ve got a planted 60 gal community tank that for the last month has been losing fish randomly and more so within the last week or two. It has serpae tetra, neon tetra, 3 types of rainbows, oto, a bristlenose pleco, and bronze cory.

I first lost an oto, 6 neons, and 7 new orange Venezuelan cory. The oto and neons were older fish. The oto over two years the neons even older. So I assumed that they were dying one by one of old age. The cory I got were from aquahuna and were very small so I assumed they just stressed out and were weak and couldn’t handle it. Got a refund and didn’t think any more about it. Out of concern though, I chose to rescape the tank last week just in case there was something dead caught somewhere causing issues because I only found a few bodies. I believed the rest to be eaten but better safe than sorry and the tank had been running for about a year anyway.

Then, I got 7 new neons to replace the old ones and give the remaining neon a school. They were healthy and active… and then started disappearing. Went from 8 neon to 4 to 3 to none within a few days. Even the old one was gone and I only found maybe 3 corpses. Then a serpae tetra died. And now I had a turquoise rainbow die this morning and another with a white patch on its side that I assumed was a scratch. I now have him in a 2 gal bucket with methalyne blue, paraguard, and a dose of erythromycin. He’s the first to have a sign of anything physical wrong. No one else has nor their corpses.

Parameters were checked yesterday. 0, 0, 30. Temp is just below 80F/26.7C. Water changes are weekly or every other week with a filter clean (I rinse in tank water) every month. Ph is 7.4. Feeding is every other day with omega one flakes and omega one sinking pellets for Cory with an occasional algae wafer for pleco. Only thing that’s changed the last month other than the rescape is I went from Thrive + to Thrive C for plant fertilizer.

And unfortunately I do not have a quarantine tank. My options are limited when I live with my parents who want me to be rid of the tanks anyway. So all new fish are floated with tank water added every 15 min for an hour. I make sure they have no physical signs of issues and then closely monitor them once they are in the tank. All new fish were colored up quickly, active, and ate for days after they were added. I saw no issues until they went missing about 5-7 days later

pictures of the tank are attached as well as the dead turquoise from this morning and the one I have separated for their seeming injury.

Very nice looking tank!

However, in the image of the fish from overhead, there are clear signs of scales being raised away from the body, though it’s not severe at this point. That is never a good sign to see. Is that the fish that you’re medicating?

I think you really need to start doing 50% water changes a minimum of once a week, because having NO3 at 30 before a water change with plants in the tank isn’t what you want to see. You want to see NO3 as low as it can kept and ideally never higher than 20 maybe and ideally under 10ppm.

The fish in the cup does not look bloated so it might be a very early case of infection causing kidney damage and treating that kind of thing is most often not successful, sorry to say.

Also, what is your rationale for feeding only every other day? Lots of fish keepers skip feeding one day as week, some skip two, but skipping every other day is not going to give fish robust good health and I suspect has made them weak compared to fish that are fed more regularly.

Lastly, that’s a LOT of medication to use all at one time. I can’t see the white patch you mention but using erythromycin isn’t a great idea unless you’re trying to treat an eye infection as it’s best on gram positive bacteria and with the exception of the eye, fish infections are gram negative.

Not only that, ParaGuard contains malachite green, so if you’re going to use that, I’d have skipped the meth blue.

I would have applied meth blue alone to the patch, directly as it comes from the bottle, which would tell me if the slime coat in the area is intact or not. If it’s intact, there’ll be no blue stain on the fish and that tells me it’s not a skin infection.

If it did stain the area blue, that tells me the slime coat is compromised and that the spot could be infected and then I’d have to consider what else to use, if anything.

If you think it’s a fungal patch, MB is about as good a fungal treatment as we have to use and used directly it’s incredibly effective and quick to work. It’s useful for mild bacterial infections too and because it is not an antibiotic, it does not contribute to antibiotic resistance - which is why I hate to see any antibiotic used unless there’s no other choice or you’re very sure of what you’re treating and know it’s likely to help.

 

Not sure if this helps, but I use a 10 and 15 gallon sterilite storage tub/tote for quarantine. When not in use I pack up my fish stuff in them. When I need them I put everything into a reusable grocery bag and use the tub. Very cheap and easy to get and only temporarily takes up a little room, not sure if that's something you could fit in your bedroom.

The lack of quarantine could potentially bring in things you'd not want there. The cause for this I don't really know, but hopefully someone else will have a better idea of what's happening.

You want to keep nitrates under 20 ppm at all times with fresh water fish. I'm not sure if there's any exceptions for certain species. By the time you do a water change you want it no higher than 20 and bring it down to what you need it to be before it builds up again.

I would do extra water changes to get this nitrates down in the mean time.

I've always had issues with high nitrate but I never let it get above 40. Given I can't use a python for draining due to our sink fixture (and the hose outside having a high ph of over 8) I'm doing every water change with a 2 gal bucket. This means I can't remove as much water as I would like to keep nitrates lower than about 30 in my big tanks. My smaller tanks are about 20. I don't know if it's just from the source water (I use tap) or if it's because of the plant fertilizer I use but I can never get it below 20ppm except in my betta tank... somehow.

All I have on hand is a 5 gal home depot bucket that I use to hold some fish stuff and my 2 gal bucket (which is being used for quarantine for that injured rainbow at the moment). I'll see if I can maybe get something to quarantine with that's bigger but I had fish deaths happening before I got new fish so I'm not sure what's happening.

 

I've always had issues with high nitrate but I never let it get above 40. Given I can't use a python for draining due to our sink fixture (and the hose outside having a high ph of over 8) I'm doing every water change with a 2 gal bucket. This means I can't remove as much water as I would like to keep nitrates lower than about 30 in my big tanks. My smaller tanks are about 20. I don't know if it's just from the source water (I use tap) or if it's because of the plant fertilizer I use but I can never get it below 20ppm except in my betta tank... somehow.

All I have on hand is a 5 gal home depot bucket that I use to hold some fish stuff and my 2 gal bucket (which is being used for quarantine for that injured rainbow at the moment). I'll see if I can maybe get something to quarantine with that's bigger but I had fish deaths happening before I got new fish so I'm not sure what's happening.

Have you got a shower? You can hook up a Python to a shower arm if you can’t get an adaptor to fit the sink - I have the same problem.

All I needed was a diverter for the shower arm, so I can just flip the switch for the shower or to send the water into the hose - and I hooked up the hose from a hand held shower to the diverter because I have some trouble reaching that high. Easier to deal with the hose than try to attach anything up over my head.

Shower arms and shower hoses all have 1/2“ NPT threading. All you need is an adaptor that fits the shower hose on one side and the python on the other. Flip the switch and you’re all set to use the Python.

I cannot even imagine doing changes with a 2G bucket!

I do wonder if feeding every other day has weakened the fish and contributed to some of the deaths- why do you choose to feed that way?

 

Very nice looking tank!

However, in the image of the fish from overhead, there are clear signs of scales being raised away from the body, though it’s not severe at this point. That is never a good sign to see. Is that the fish that you’re medicating?

I think you really need to start doing 50% water changes a minimum of once a week, because having NO3 at 30 before a water change with plants in the tank isn’t what you want to see. You want to see NO3 as low as it can kept and ideally never higher than 20 maybe and ideally under 10ppm.

The fish in the cup does not look bloated so it might be a very early case of infection causing kidney damage and treating that kind of thing is most often not successful, sorry to say.

Also, what is your rationale for feeding only every other day? Lots of fish keepers skip feeding one day as week, some skip two, but skipping every other day is not going to give fish robust good health and I suspect has made them weak compared to fish that are fed more regularly.

Lastly, that’s a LOT of medication to use all at one time. I can’t see the white patch you mention but using erythromycin isn’t a great idea unless you’re trying to treat an eye infection as it’s best on gram positive bacteria and with the exception of the eye, fish infections are gram negative.

Not only that, ParaGuard contains malachite green, so if you’re going to use that, I’d have skipped the meth blue.

I would have applied meth blue alone to the patch, directly as it comes from the bottle, which would tell me if the slime coat in the area is intact or not. If it’s intact, there’ll be no blue stain on the fish and that tells me it’s not a skin infection.

If it did stain the area blue, that tells me the slime coat is compromised and that the spot could be infected and then I’d have to consider what else to use, if anything.

If you think it’s a fungal patch, MB is about as good a fungal treatment as we have to use and used directly it’s incredibly effective and quick to work. It’s useful for mild bacterial infections too and because it is not an antibiotic, it does not contribute to antibiotic resistance - which is why I hate to see any antibiotic used unless there’s no other choice or you’re very sure of what you’re treating and know it’s likely to help.

The fish in the cup is the fish I'm medicating. I used multiple medications because I'm not sure what the cause is and assumed having more is better than not having anything. The white patch isn't coming up on picture well but it's on the left side of the fish where the scales are raised. That's why I assumed it was a scrape and not an infection of some kind.

I'm feeding every other day because when I was feeding every day the fish appeared bloated more often than not. I've not had any issues feeding every other day and have been for over a year. It's hard for me to determine how much to feed them since they're in a community tank and the rainbows eat all the flakes so quickly that they then go after the sinking pellets for the cory, thus overfeeding themselves. So, I assumed giving them a day to digest before feeding them again would prevent that.

So, what would you suggest I do? Should I take the medicated fish out, spot treat with MB, and put back in the 2 gal bucket (which has a heater and air bubbler) with fresh water unmedicated? I'm assuming I wouldn't put it back in the community tank until I know what's wrong. And I'm open to suggestions about the feeding too. My main concern was the fish being overfed.

Have you got a shower? You can hook up a Python to a shower arm if you can’t get an adaptor to fit the sink - I have the same problem.

All I needed was a diverter for the shower arm, so I can just flip the switch for the shower or to send the water into the hose - and I hooked up the hose from a hand held shower to the diverter because I have some trouble reaching that high. Easier to deal with the hose than try to attach anything up over my head.

Shower arms and shower hoses all have 1/2“ NPT threading. All you need is an adaptor that fits the shower hose on one side and the python on the other. Flip the switch and you’re all set to use the Python.

I cannot even imagine doing changes with a 2G bucket!

I do wonder if feeding every other day has weakened the fish and contributed to some of the deaths- why do you choose to feed that way?

I have a shower but it's a ways away from where I have the tank. I'd need a really long python and I'm not sure how pleased my parents would be if I were to be screwing and unscrewing the head on the shower arm. I also don't know the ph for the shower. My kitchen tap is about 7.4. The hose outside is 8+. And the shower is hooked up to a separate system than the kitchen tap. I'd have to test it to see.

 

The fish in the cup is the fish I'm medicating. I used multiple medications because I'm not sure what the cause is and assumed having more is better than not having anything. The white patch isn't coming up on picture well but it's on the left side of the fish where the scales are raised. That's why I assumed it was a scrape and not an infection of some kind.

I'm feeding every other day because when I was feeding every day the fish appeared bloated more often than not. I've not had any issues feeding every other day and have been for over a year. It's hard for me to determine how much to feed them since they're in a community tank and the rainbows eat all the flakes so quickly that they then go after the sinking pellets for the cory, thus overfeeding themselves. So, I assumed giving them a day to digest before feeding them again would prevent that.

So, what would you suggest I do? Should I take the medicated fish out, spot treat with MB, and put back in the 2 gal bucket (which has a heater and air bubbler) with fresh water unmedicated? I'm assuming I wouldn't put it back in the community tank until I know what's wrong. And I'm open to suggestions about the feeding too. My main concern was the fish being overfed.

I get that but there’s such a thing as underfeeding too. Since you have MB, it would be useful to know if it’ll stain that white spot or not. If you can net the fish, flip some net over it just long enough to use a syringe or dropper to apply some MB and then back into the water. Then see if there’s any stain.

I’d bet they’re greedy, they’re really hungry! Maybe try putting food at both ends of the tank or even 3 or 4 spots around it all at about the same time, to help distract some of the larger fish so they’re less likely to dive for the bottom and steal from the cory cats and for now, I’d make sure that whatever you feed, it’s something they all like so the food at the bottom isn’t more appealing than the food up top Is.

You could try placing sinking food for the catfish in small, out of the way spots where it’s not so obvious to the larger fish and that might help. But I would feed at least 6 days a week.

Fish can become obese if overfed but it usually doesn’t cause bloating. In some fish you can see the stomach is full and then later it’ll have gone back to normal but there’s nothing wrong with that, it’s normal.

 

Welp. He was upside down when I went to do it. Alive still but barely. I dripped some MB on him and put him back and he died a moment later. Here’s pics to show the staining. It was mostly on the left side where the spot was. And a tiny bit on the right. Still not sure what’s going on. All other fish in the tank are active so here’s hoping he’s the last of my fish losses. Just wish I had a clue what’s happening. No other fish had any physical signs of anything.

 

Welp. He was upside down when I went to do it. Alive still but barely. I dripped some MB on him and put him back and he died a moment later. Here’s pics to show the staining. It was mostly on the left side where the spot was. And a tiny bit on the right. Still not sure what’s going on. All other fish in the tank are active so here’s hoping he’s the last of my fish losses. Just wish I had a clue what’s happening. No other fish had any physical signs of anything.

I wish I could say I was surprised but with scales poking out like his were, the chances were not good. Looks like he’s actually got a lot of slime coat missing but that may be a artifact of the raised scales themselves.

My condolences.

 

I wish I could say I was surprised but with scales poking out like his were, the chances were not good. Looks like he’s actually got a lot of slime coat missing but that may be a artifact of the raised scales themselves.

My condolences.

It was quick, whatever it was. The white patch showed up two days ago; no raised scales. He was acting fine yesterday and this morning he was slightly slower and the scales were raised. I feel bad for the last remaining turquoise rainbow who's now the only one in there (with my 3 Australian and 3 boesemani).

 

It was quick, whatever it was. The white patch showed up two days ago; no raised scales. He was acting fine yesterday and this morning he was slightly slower and the scales were raised. I feel bad for the last remaining turquoise rainbow who's now the only one in there (with my 3 Australian and 3 boesemani).

Hopefully feeding more will help and if you do have a shower, consider using it to hook up the python so you can do larger and more frequent water changes without half killing yourself lugging wee buckets back and forth.

 

Just doing a quick search about Nitrate poisoning and I'm reading that that too can cause weakened immune systems at 30 ppm.

I've just been reading a lot of similar issues where there is fish loss and Nitrates are too high.

Even if you find you can't hook up the python to your shower there are other kinds of adapters that could fit your sink.

Look up the brand of faucet you have, bring your python parts to a hardware store, and ask a worker for some tips on what to look for.

I think with more feedings as Fishfur mentioned coupled with bigger water changes and keeping it under 20 ppm will make a world of difference.