Mysterious Cory Catastrophes

[Becky412]

Hello, I need to pick your brains. I have a 36 gallon bowfront and 55 gallon. Both are set up with the same substrate ( pea gravel), cannister filters and 2 power head - one at water line and one low along the back wall as well as artificial and live plants.  I feed every other day, both tanks.  Foods I alternate between is flake, wafers, frozen bloodworms and other frozen food, tubiflex worms.  Trying to find shrimp wafers.

My 55 gallon as 12 quarter to half-dollar size juvenile angels (will be thinning out), 4 three inch bushynose plecos and 6 small spotted cory - all living, thriving and happy. Rocks for decor and plant attachment and a faux tree stump for hiding spot(s).

My problem is my 36 bowfront. I am having consistent cory deaths/MIAs.  As I said it is set up mechanically the same. It is stocked with 3 red & blue columbian, 2 lemon and 3 del rio tetra, 2 bushy nose pleco and currently, that I can find, 2 (I think - I can find one) panda's left, some rocks (for plant attachment) and faux rock structures for hiding.

I have lost 6 albino, and 6 panda. I have only found 2 dead and the rest came up MIA. Yesterday I was feeding and the lastest loss spiraled to the top of the tank, went back to the bottom, rolled over and died before I could get it netted out and put into a medication bath. When I buy them, I have quarantined them for a couple of weeks and they are fine. I accliment and move them to this tank and stuff happens within a day or two.

Specifics you are going to ask about:

Water source is well and was tested in September and was clear.


API Testing: pH - 7.2; Ammonia - 0; Nitrite - 0; Nitrate - 10; kH - (2 drops) 0-50; gH - (3 drops) 50-100; phos 1.0

Water change - 9/22 - approx. 30-40% - API stress coat (because I am sure water changes can cause stress)

Substrate vacuum 9/22 - Seachem prime (because vacuuming can stir up the ammonia/nitrate values)

Cannister filter was opened and rinsed in tank water last week.

I have prefilter on intake - no fish attached.

All fish doing fine.

 

Maintenance performed on 55 gallon same day - 

Water change - 9/22 - approx. 30-40% - API stress coat (because I am sure water changes can cause stress)

Substrate vacuum 9/22 - Seachem prime (because vacuuming can stir up the ammonia/nitrate values)

Cannister filter was opened and rinsed in tank water last week.

I have prefilter on intake

Everyone happy, healthy and beggng for food as they normally do.

So, I am at a loss as to what is going on. Anyone have any thoughts?  Hoping Cory will see this and chime in so I can get hs perspective.

 

 

Edited September 24, 2022 by Becky412

[Anjum]

Man, that is strange! I'd think a contaminant, but that seems unlikely if the other fish are doing fine. You've got aeration to the bottom of the tank? A bowfront is more of a deep tank, less air exchange making it down there from the top than I'm a shallower tank. 

[Becky412]

Yes, it is slightly taller than my 55.   I have a powerhead at water level, and another one at bottom corner moving water along the back wall.  Also, the spraybar is tilted forward amd slightly down.  Have same set up on 55.

Edited September 24, 2022 by Becky412

[Becky412]

Although I did just  measure the 2 tanks.  The 36 bow front stand is taller, but both tanks have 19" of water in them.  So depth should not be a problem.

[Colu]

It's possible with you only feeding every other day they come be getting out competed by the other fish and not getting enough food and eventually getting weak and dieing did any of the ones that died have a sunken belly 

[Becky412]

I feed both tanks the same.  Because pellets can get lost on the crevices of the gravel, I feed wafers & sticks appropriate for corys.  I feed flake food and some frozen bloodworms and shrimp as that stays on top of gravel.   

 

I have only found 2 that died and their bellies didnt seem sunken, but had a red hue.  

[meadeam]

Did the cories who perished join the tank together, or did they come in at different Intervals?  Did they all come from the same store or breeder?  A common link that only they share might provide a clue if not an explanation.

[Becky412]

The albinos were first bought from my "local" fish store 1 hour away.  There were 3, 1 survived.  I bought 2 more albino (from PetsMart- yeah, yeah I know  🙄) so the single one would have friends and bought 3 panda at sime time.  After quarantine, added those 5, 1 panda survivied.  Bought 3 more panda (from PetsMart) and 6 spotted (from different fish store) to put in the 55 gallon.  I currently have 2 panda left in the 36 gallon and all 6 survived in the 55,

 

 

[nabokovfan87]

Does either tank have an airstone?

I am going to guess here, either what @Colu was hinting at is likely or something like the combination of that, temp, and oxygenation.

Taller tanks can be a bit difficult for some corys because of the flow / movement.  It's "better" because taller tanks give them a bit cooler water at the substrate. However, if the tank temp itself is just too high it might stress them out.  This is where you would see rapid breathing, and you'd want to have extra oxygenation.  As the water gets warmer it holds less oxygen (slightly).

[Becky412]

And NOW there is 1.  This morning both happily scooting around foraging.  Now........  I do not see any of the fish bullying them.  The plecos are doing their thing, the Tetra are doing their thing.  Right or wrong I moved it to the 55 gallon since that seems to be the tank where staying alive is best.  

[nabokovfan87]

On 9/24/2022 at 12:28 PM, Becky412 said:

I feed both tanks the same.  Because pellets can get lost on the crevices of the gravel, I feed wafers & sticks appropriate for corys.  I feed flake food and some frozen bloodworms and shrimp as that stays on top of gravel. 

They will have the easiest time eating the flake and the worms.  I'd recommend utilizing a feeding dish with the substrate you have.  This can be a ceramic pot dish or glass dish you might happen to have available.

The red belly is very concerning and points towards internal damage to the corydoras in some method.  This could be from trying to dig in the hard / heavy gravel as well as other methods they are interacting with the hardscape.  As mentioned above, flow + Tank height does play a role and they could smash into the glass lids at times if the water is very high.  This would be damage on their nose, not necessarily on their belly.  Their bellies usually show damage from the substrate / laying on the substrate that is sharp.  This also could be internal damage and you're seeing the blood or swelling as a result. 

Temps? Airstones?  What are we looking at here?

[Becky412]

Both the 55 and 36 have 19 inches of water - bottom of substrate to top of water line.  Temp is currently 77.4.   There is a powerhead at water line for circulation and one on lower corner pushing water across back wall.  Spray bar is point forwad and slightly down.  This is the same for both aquariums - and of course the 55 is longer and no issues.

[Colu]

Did any of the other Cory's that died have the this Redding on their body 

[Matt_]

Sorry for your loss.  Those are nice looking tanks.  I have a question and a couple of things to check from personal experience.

I have kept Corys with sharp rocks and substrate in a 2' deep tank for years so I tend to doubt either is contributing to the issue. 

Were the API test results in the initial question identical for both aquariums?  It is strange that there is no measurable ammonia in the 36 gal. at this point with those losses - I usually get minor indication from the API liquid Ammonia test kits no matter what I do.  Recommend ensuring that the testing liquid is well shaken prior to testing if you are using the API liquid test kit and retest the 38 gal for Ammonia and Nitrite.  If the Corys are doing well in the 55 gal. using the same well water, then the issue should not be an undetectable parameter with the well water (like salt, heavy metals, or industrial pollutants).

Other quick checks: recommend independently checking the tank temp. again to rule out a faulty heater/thermometer if you are using an electronic thermometer.  Confirm all foods, especially the sinking pellets/wafers, are unspoiled and less than a year old (preferably younger than that, but it is a start).  The water temperature of the well water could be a factor at a 40% water change if it is significantly warmer or colder than the tank water assuming you checked this by feal at the water changes.

If the water tests for Ammonia and Nitrite are still reading at 0 in the 38 gal. and GH/KH is not elevated one idea would be to check for stray current from the powerhead/heater.

[Anjum]

On 9/24/2022 at 4:07 PM, Matt_ said:

one idea would be to check for stray current from the powerhead/heater

Yes! I always forget about this. I've heard of multiple people having mysterious fish ailments or death due to stray current. Some fish just seem to be worse affected by it than others. 

[nabokovfan87]

On 9/24/2022 at 2:30 PM, Becky412 said:

 There is a powerhead at water line for circulation and one on lower corner pushing water across back wall.  Spray bar is point forwad and slightly down.  This is the same for both aquariums - and of course the 55 is longer and no issues.

Flow is very different than oxygenation.  This is why I am specifically asking about an airstone / surface agitation.  The powerhead that is lower likely has a very direct output and very likely is what caused the redness.  If we don't have a guess as to the other cause, I'm willing to bet that is a contributing factor to that damage internally / belly redness.

[Matt_]

You should be able to stray current if you have a multimeter, but I doubt it is the issue since the fish are not behaving erratically.  Just trying to think through why only the Corys are not doing well in only the 36 gal tank vs. the 55 gal.  @nabokovfan87 oxygenation comment also is worth considering.  One way to check is to see if the tetras and plecos are all at or near the water surface at night (with no stray light).

[Becky412]

On 9/24/2022 at 6:17 PM, Colu said:

Did any of the other Cory's that died have the this Redding on their body 

The ones that I have found did.

On 9/24/2022 at 8:08 PM, nabokovfan87 said:

Flow is very different than oxygenation.  This is why I am specifically asking about an airstone / surface agitation.  The powerhead that is lower likely has a very direct output and very likely is what caused the redness.  If we don't have a guess as to the other cause, I'm willing to bet that is a contributing factor to that damage internally / belly redness.

I just added the lower power head 2 days ago.  The die off/MIA has been happening.

On 9/24/2022 at 8:17 PM, Matt_ said:

You should be able to stray current if you have a multimeter, but I doubt it is the issue since the fish are not behaving erratically.  Just trying to think through why only the Corys are not doing well in only the 36 gal tank vs. the 55 gal.  @nabokovfan87 oxygenation comment also is worth considering.  One way to check is to see if the tetras and plecos are all at or near the water surface at night (with no stray light).

I have had my hands/arm in the aquarium many times to lift the decor or artificial plants looking for fish/bodies and no shock

[Becky412]

On 9/24/2022 at 7:07 PM, Matt_ said:

Sorry for your loss.  Those are nice looking tanks.  I have a question and a couple of things to check from personal experience.

I have kept Corys with sharp rocks and substrate in a 2' deep tank for years so I tend to doubt either is contributing to the issue. 

Were the API test results in the initial question identical for both aquariums?  It is strange that there is no measurable ammonia in the 36 gal. at this point with those losses - I usually get minor indication from the API liquid Ammonia test kits no matter what I do.  Recommend ensuring that the testing liquid is well shaken prior to testing if you are using the API liquid test kit and retest the 38 gal for Ammonia and Nitrite.  If the Corys are doing well in the 55 gal. using the same well water, then the issue should not be an undetectable parameter with the well water (like salt, heavy metals, or industrial pollutants).

Other quick checks: recommend independently checking the tank temp. again to rule out a faulty heater/thermometer if you are using an electronic thermometer.  Confirm all foods, especially the sinking pellets/wafers, are unspoiled and less than a year old (preferably younger than that, but it is a start).  The water temperature of the well water could be a factor at a 40% water change if it is significantly warmer or colder than the tank water assuming you checked this by feal at the water changes.

If the water tests for Ammonia and Nitrite are still reading at 0 in the 38 gal. and GH/KH is not elevated one idea would be to check for stray current from the powerhead/heater.

API tests have been identical.  In fact, the 55 gallon nitrates were a little higher before the water change.

Ammonia is negative - bright yellow when tested and checked after 5 minutes.

Ammonia instructions do not indicate that it needs to be shaken, although I do give it a good 10 second shake.  I use a timer with the 30 second initial shake for nitrate and then times 1 minute shake before letting set for 5 minutes.

I have tested my well water using the API and all is negative and like I said, I just had my well tested.

Digital thermometer currently says  - 77.9; infared thermometer registers 78.2; no heater in use at this time.

Foods have all been bought in past 2 months.  Both tanks fed same food.

When I do a water change, regardless of how much, I always try and match the temp of the water going into the tank as close as possible to the current tank water and use the infared thermometer.

Have had my hands in the water many times lifting the decor and artifical plants looking for bodies.  And yes, I always wash my hand/arms before immersing them.

 

Thanks for the repsonse.

 

 

[Matt_]

On 9/24/2022 at 8:43 PM, Becky412 said:

API tests have been identical.  In fact, the 55 gallon nitrates were a little higher before the water change.

Ammonia is negative - bright yellow when tested and checked after 5 minutes.

Ammonia instructions do not indicate that it needs to be shaken, although I do give it a good 10 second shake.  I use a timer with the 30 second initial shake for nitrate and then times 1 minute shake before letting set for 5 minutes.

I have tested my well water using the API and all is negative and like I said, I just had my well tested.

Digital thermometer currently says  - 77.9; infared thermometer registers 78.2; no heater in use at this time.

Foods have all been bought in past 2 months.  Both tanks fed same food.

When I do a water change, regardless of how much, I always try and match the temp of the water going into the tank as close as possible to the current tank water and use the infared thermometer.

Have had my hands in the water many times lifting the decor and artifical plants looking for bodies.  And yes, I always wash my hand/arms before immersing them.

 

Thanks for the repsonse.

 

 

Ok, responses are what I expected; looks like temp. water, food, etc. is normal and within range for those Corys.  As a side note, I have gotten to the point where I just shake all the liquids when I use the API test kits so that I don't have to remember which ones require shaking 🙂.

Low oxygenation may have been the issue even with a powerhead.  Two powerheads is a lot of flow for a tank that size.  A quick way to check is to see if the tetras and plecos are all at or near the water surface at night when they are typically less active (checking with a flashlight in a dark room).  If there is an oxygen deficiency then the fish will be behaving differently (i.e.: swimming lethargically, breathing surface air).

After that I am out of ideas and hope that transitioning the fish to the 55 gal fixed the issue.

[Becky412]

On 9/24/2022 at 9:05 PM, Matt_ said:

Ok, responses are what I expected; looks like temp. water, food, etc. is normal and within range for those Corys.  As a side note, I have gotten to the point where I just shake all the liquids when I use the API test kits so that I don't have to remember which ones require shaking 🙂.

Low oxygenation may have been the issue even with a powerhead.  Two powerheads is a lot of flow for a tank that size.  A quick way to check is to see if the tetras and plecos are all at or near the water surface at night when they are typically less active (checking with a flashlight in a dark room).  If there is an oxygen deficiency then the fish will be behaving differently (i.e.: swimming lethargically, breathing surface air).

After that I am out of ideas and hope that transitioning the fish to the 55 gal fixed the issue.

So, what do you think about my theory that the decorations are trapping water in the dead space above the openings and water not being circulated out like my tree trunk in 55 gallon that has openings everywhere and no dead space.  Only problem I have with that theory is, again, the other fish are not affected.

Going to try and drill some holes in the very top of the decoration on the back side tomorrow and hopefully not destroy the piece in the process.  But, if I do, I do.  Just have to buy something else.

[Matt_]

Dead space for water flow is not an issue; oxygenation is different.  Please don't drill holes in your decorations.

I have a 38-gallon heavily planted aquarium with 100 or more guppies and about 30 Paleatus Corys that only has two airstones for aeration and tons of dead spaces everywhere.  I also have a 65-gallon tank with a huge hollow log with plecos, corys, and clown loaches living nook and before that the same fish lived in a castle decoration.

[Colu]

On 9/25/2022 at 1:31 AM, Becky412 said:

The ones that I have found did.

It's could be Red blotch disease it's common in Cory's he's some information the most effective treatment is a broad spectrum antibiotic treatment such as kanaplex or maracyn2 

[Matt_]

Never seen red blotch disease before but the photos on Google (may not be accurate) sure seem resemble the photo of the fish above.

[nabokovfan87]

Not sure this fits.  What Colu mentioned might be on target. 

Fish are stressed, tired, low oxygen (comparatively) and then you add a powerhead.  They rush to the surface to get air, sometimes, and because it's a tall tank it can be stressful on an already stressed corydoras.  They smack the lid, causing internal damage.  It happens.  Happening to every fish isn't likely but if you're keeping the waterline near top of the rim, I can see it happening.  Then.... fish are trying to hold on and keep going and you add a powerhead.  Stressed fish, under more stress because of the added flow it needs to swim against.  The photo you showed had a cory with it's tail almost 30-50% completely gone.  That fish had some pretty severe issues to be in that shape, whatever the cause of it.  I can't speak to what the others looked like, but whatever is the cause of all these issues there's a few things I would highly recommend doing right now.

1.  Add an airstone if you can.
2.  Add a feeding dish for corydoras with this gravel
3.  If you can, if you don't have a risk of killing plants, probably add some aquarium salt.
4.  Treat with general antibiotics like Colu mentioned.
5.  Treat for fungal with Ich-X and follow the directions on the bacteria medications.  If it says to change water on the third day, you'd change the required volume and re-dose with Ich-X as well as the bacterial meds.

Because you're having such severe issues, I would highly recommend having a QT tank setup and use it on any new fish you purchase.