Pygmy Cory - Not thriving (pale)

[tam]

I'm not sure how clear it is from the photo but I don't think these pygmy cories are really thriving. Not sure how clear it is from the photo, but the one on the right and second from the right have gone very pale. I started with nine a few months ago, and now down to six.

They are in a 70l, rain + tap (TDS about 120), and the water in a bit tannin stained from oak leaves. I feed bug bites.

Any ideas?

 

[hypnogogia]

No photo…

 

[tam]

Oops, just attached it

 

[Hufsa]

Bacterial infection / general high bacteria pressure in the tank? Its not clear from the photo but how are the barbels looking? Are the tail fins a little short as well?
Corydoras sometimes seem (to me) to be more prone to getting sick if theres some unfavorable build up in a tank, I think its simply because they spend so much time on the bottom, they're always in that "zone" if you know what I mean.

 

[tam]

Bacterial infection / general high bacteria pressure in the tank? Its not clear from the photo but how are the barbels looking? Are the tail fins a little short as well?
Corydoras sometimes seem (to me) to be more prone to getting sick if theres some unfavorable build up in a tank, I think its simply because they spend so much time on the bottom, they're always in that "zone" if you know what I mean.

The tails look fine, but the barbels on the pale ones look short, but fine on the others - so I'm not sure if it's just a symptom of the issue rather than the cause. I'll try and get a better photo tomorrow when the lights ramp back up.

I've some very little patches of cyano bacteria in spots, but generally the substrate isn't obviously mulmy.

 

[dw1305]

Hi all,

They are in a 70l, rain + tap (TDS about 120), and the water in a bit tannin stained from oak leaves. I feed bug bites.

Any ideas?

Similar parameters to mine. Iwonder if a more varied diet might help? Mine get Grindal & Micro worms, Daphnia, freeze dried Copepods and Astax crumb, as well as Bugbites.

Cheers Darrel

 

[Conort2]

You’re right, they definitely look “off”. How are the sundadanio that I can see in the background of your photo.

Could be worth treating for internal parasites.

 

[dino21]

What kind of sand do you have, bit hard to tell from your photo, but it looks quiet course, you could try adding surface layer of silver sand like Unipac.
Know a lot of folk use BugBite, but find our dwarfs like flake food crushed up best, seems a lot softer for them to eat.

 

[Hufsa]

What kind of sand do you have, bit hard to tell from your photo, but it looks quiet course, you could try adding surface layer of silver sand like Unipac.

The sand itself looks fine to me, its not likely that the grain size itself is whats causing the corydoras problem. Also these are tiny fish, so the sand looks bigger than it is, I think its actually pretty fine grain.
Gravel or sand grain size is not really the issue with Corydoras health (but fine grains are still recommended so they can sift naturally). Of course the grains should not be sharp, but the size isnt the only factor.

What makes or breaks a substrate is the "health" of it. This applies to both gravel and sand. If there is excessive buildup of harmful bacteria in the substrate then it will start to wear on the corys. It usually starts with barbels and fins before progressing to a whole-body issue.

@tam does your sand have any trumpet snails? How old is the current setup?
A bit more general information about the tank overall would be a help 😊

The tails look fine, but the barbels on the pale ones look short, but fine on the others - so I'm not sure if it's just a symptom of the issue rather than the cause. I'll try and get a better photo tomorrow when the lights ramp back up.

Barbels are definitely a symptom not a cause, I agree. But I think whats causing the barbels to be short might also be causing the overall sickness of those individual fish. Whether that is a lowered immune system from some other factor or from a substrate issue. Its hard to say at this point.
Have the losses been gradual over time or did it peak at some point?
Possibly whatever this is, is working its way through the group starting with the weakest fish first?

I've some very little patches of cyano bacteria in spots, but generally the substrate isn't obviously mulmy.

Pictures of this as well would be good 👍

 

[tam]

Thanks for the ideas, here are the answers to questions...

The tank was set up September 2021 so approx 18 month old. It's 1-2mm fine gravel at the bank and sand at the front. There is a thin layer of tropica substrate under the gravel. The crypt/sword roots are all over the tank.

No trumpet snails, but there are pond snails. Otherwise the inhabitants are one sudadanio (I mail ordered them and they came in tiny with one dead in the bag and a couple on the way out the rest didn't last long) the survivor I would describe as large and plump. And one cory napoensis - I got six cory napoensis at the same time and lost a few stright off and the others over a couple of months with one left. Again the last one is pretty healthy looking. I added the pygmys November time last year and they've looked fine, not grown much but I've not kept them before so that might be full size (not looked skinny though) until the last month, the dealths were gradual - actually recounted and there is seven so only lost a couple who looked fine at the time but there are two very pale ones. Maybe there is something that's effecting cories - I assumed the napoensis were a bit sensitive as they aren't that common.

I always grind the bug bites up a bit as they are so dinky. Will they fit grindle worms in their mouths? Happy to expand the food range.

I will pop some pics on, just need to find a card reader.

 

[Gerald Buswell]

I would guess this is bacterial, sand can cause issues, you need to regularly rake through it, and add trumpet snails to help keep it from compacting and healthy. I keep many species of Corydoras over sand, but it is not deep and I turn it over, something that is not always practical in a planted tank, which is why snails will help.

 

[dw1305]

Hi all,

I always grind the bug bites up a bit as they are so dinky. Will they fit grindle worms in their mouths? Happy to expand the food range.

That is <"what I do"> with the Bugbites as well, and "yes "they slurp them up like Spaghetti.

cheers Darrel

 

[Conort2]

got six cory napoensis at the same time and lost a few stright off and the others over a couple of months with one left.

Something isn’t quite right then, sundadanio can be quite fragile but to lose corydoras napoensis is a bit of surprise. I’d class these as pretty hardy.

gradual but continual deaths would point more to an internal parasite, although I could be wrong.

 

[X3NiTH]

I keep Salt and Pepper Corys, while a little larger than Pygmy’s they have no problem slurping up live bloodworms and tubifex, the worms get savaged before they’ve had a chance to bury themselves in the sand, once the corys (and everything else) are done with the worms they move on to the bug bites. I also dose frozen cyclopia/copepods for my Celestial Pearl Danio shoal and any that make it to the substrate the Corys finish off. They’re a fat bunch!

If there is a worry about internal parasites then you can adulterate some of the bug bites with an anti parasitic before feeding to ensure it passes through the gut of the fish to clear any digestive issues, I’d vary the diet first.

 

[dw1305]

Hi all,

They’re a fat bunch!

They look super healthy, fat and a good colour.

cheers Darrel

 

[tam]

Got some better photos using camera rather than phone.

I've got some frozen copopods I've fed occassionally. I will up that and see if I can order grindal worms to start a culture.

What else should I be doing? The pale ones are still coming out to feed.

 

[Hufsa]

I still suspect the substrate. Not the sand+gravel itself but I think it doesn't have a good kind of microbes/bacteria currently.
Im seeing cyanobacteria in small flecks all over, which cant be good for the fish to swim in constantly.
I would give the substrate a light vacuum, get some sand snails (MTS) in there and try to increase the flow right above the substrate. It doesn't have to be a strong current, just enough to get the water circulating a bit more.

More and bigger water changes might be a good idea as well, to help the fish that aren't doing well to hopefully recover.

 

[tam]

I still suspect the substrate. Not the sand+gravel itself but I think it doesn't have a good kind of microbes/bacteria currently.
Im seeing cyanobacteria in small flecks all over, which cant be good for the fish to swim in constantly.
I would give the substrate a light vacuum, get some sand snails (MTS) in there and try to increase the flow right above the substrate. It doesn't have to be a strong current, just enough to get the water circulating a bit more.

More and bigger water changes might be a good idea as well, to help the fish that aren't doing well to hopefully recover.

I disturb the top surface but it's very dense with roots so difficult to go any deeper with out disturbing them and having loads of fine roots then stuck out of the sand. The sand is less than an inch total. I will rotate the filter outlet so it points down so if that alters the flow, it's directed along the back of the tank so no direct flow along the front. I'm not very keen on adding MTS accidently got one in a quarantine tank, must have hitchhiked in a bag from the last and the numbers went crazy in no time and they pop out the substrate and crowd the food. I could add some shrimps?

I've done another water change yesterday and will do more.


Should I be adding something in terms of treatment for the pale ones?

 

[zozo]

Could be an external parasite such as Trichodina... Early signs of this infection start with losing colour, as goes for most fish, getting pale because of not feeling well and being irritated. In a later stadium and a worse infection is followed by flashing and scratching against surfaces, and then excisive secretion of mucus of the skin and or fin rot. If the parasite nests in or around the eye it will go blind and probably permanently lose this eye. Followed again by brain/nerve damage erratic behaviour and sudden death.

As far as I know, Corydoras pygmaea is wild-caught fish and is very susceptible to Trichodina infection, it might have it already when bought from the lfs and it's most likely fatal if not treated. I guess this because they are so tiny and this parasite is most likely a huge monster to them living in their skin. If the rest of the symptoms stay out then there is only one way to determine if it is this infection you should take several skin scrapes and put them under the microscope and watch out for this as shown in the picture below. Behaving like flying saucers hovering around.

Unfortunately taking a skin scrape from such a small fish most likely will cause to much damage and discomfort and will be fatal as well.

Fortunately, Trichodina infection can be cured pretty simply and effectively with a long-term 14-day dose of Praziquantel. The best product that I know to use for this is FlukeSolve from VetArk or directly from its developers fish-treatment.co.uk. This Prazi is in powder form and can safely be dosed 1 time in the recommended dosage and kept in the tank for 14 days without a water change. Even tho the description on the bag recommends a 24-hour treatment, but this is for flukes only. 14 days has no negative side effects on other fish, snails and or shrimps. It will kill Trichodina and also the hatched newborns from previously laid eggs. Therefore the 14-day marathon treatment is best for this type of monster.

All other Prazi products I know of are diluted in ethanol and are less safe and less convenient to use for long-term treatment.

It's a long shot without proper diagnosis, but since diagnosing such small fish is extremely difficult and doing nothing and taking a scrape both might be fatal anyway, it can't hurt to take a gamble and give it a try... It also helps against skin flukes and internal worms. And it's never a bad thing to have a bag of Flukesolve in the med case, since it has an indefinite shelf life if kept dry.

 

[tam]

It's a long shot without proper diagnosis, but since diagnosing such small fish is extremely difficult and doing nothing and taking a scrape both might be fatal anyway, it can't hurt to take a gamble and give it a try... It also helps against skin flukes and internal worms. And it's never a bad thing to have a bag of Flukesolve in the med case, since it has an indefinite shelf life if kept dry.

Sounds like there isn't a lot of downsides so worth a try. Would you suggest treating my other tank at the same time (ember tetra/amano/cherry shrimp) so if it is a parasite I'm not leaving a potential reinfection source? I'll have dunked equipment/swapped plants from one tank to another at some point.

I was wondering about Esha 2000 before your suggestion as that targetted bacterial infections. Any idea if that would be safe to combine? Just thinking the Flukesolve is then 14 days without a water change so if they have a secondary bacteria infection maybe that would help?