I'm feeling discouraged about my pygmy cories.

JackGulley

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So last month I got 6 pygmy cories to add to my 20gal community tank (relevant threads) with platies, zebra danios, and cherry shrimp. I really loved seeing them school at first. But, I don't think they're doing very well. Of the 6 I bought, 2 were unhealthy and died after a day or two. Another one I later had to euthanize because it was injured to the point that it couldn't swim (I think I might've hurt it while moving decorations around).

Of the 3 I have left (which I'm sure are stressed), one of them (always the biggest) is still healthy, but the other two spend most of their time laying on the substrate, and also seem to be missing the lower fork of their tail fin? I'm not sure if this is from fin-nipping at the store or if my gravel is hurting them. I'm also having difficulties feeding them, since they're so much smaller than the other fish, and don't have safety in numbers to feel safe eating alongside the larger fish.

My intention, at first, was to get more as soon as I can (although I haven't had the money to yet), thinking that once they feel safe in a school they will be more healthy and confident. But I'm starting to feel like the species in general is just too small and fragile to fit in with the rest of my tank. I'm also starting to feel disappointed with the appearance of the fish, although that might just be because I'm not seeing them school anymore.

I'm starting to wonder if I should try to take them back and get another species (like sterbai or julii) instead. When I was initially shopping I felt like these were too big (and still do a little) but I've also realized that they would be juvenile when I bought them, and by the time they were fully grown my platies might also be a lot bigger. I also like the coloration of those species better. My only concern though is that a larger species will leave less room in the tank stocking-wise, as I would also like to eventually add a panda garra at some point and that is also a larger fish.

I'm not sure what route I should choose. On one hand I feel like the sterbai/julii would be safer and more visually appealing in the tank, but on the other hand, I feel like all this might be better if I can just fix the situation with the pygmies, since I didn't feel this way before I was having trouble with them.
 
What kind of gravel do you have? All cories need a sand substrate so that would be my first step. They do like to just chill on the substrate when they're resting so that on its own may not be a concern. Perhaps change out the gravel and see how they recover before getting any more. I think pygmies can be more interesting than larger cories as they go all over the water column not just the bottom, they may be more active etc if you add more.
 
Yeah, you need sand really. I think that platies and zebra danios are not a great match for pygmy corys, so that may be an issue. They need a sedate tank. They can be a little skittish and I think with platies and zebra danios bumbling around they may be put off feeding and head for cover. I keep mine with chilli rasboras and cherry shrimp. They compete well for food even though the cherry shrimp swarm around the food.

You need to use crushed flake food and/or micro granules. They also quite like microworms and fruitfly larvae. I'd recommend NT labs micro crumb or dennerle nanogran as staple granular food. I use a large catappa leaf as a serving tray. I mix the microgranules with a little tank water and then use a pipette to squirt the suspended granules down onto the leaf. The corys snuffle around the leaf hoovering up the granules. Sometimes they can be a little skittish and will give feeding a miss, but not very often.

They are perhaps a little drab in colour but as Lcc86 says, when they are settled they are active in mid water as well as the bottom, and whilst I never got any fry due to the shrimp eating the eggs, it was cool to watch them regularly swimming through the plants and depositing eggs on the leaves. They are also very cute in that sometimes two of them will go off on their own and find a little hollow in a piece of bogwood and use it as a resting place.

Sadly, I'm now down to my last two as the others have gradually died over the last 3 years. I am not going to get any more for now as I'd prefer to keep a larger school of chilli rasboras rather than limit the number of chillis to keep the corys.

They seem perfectly happy with just the two of them, although a larger group is recommended and will look far better.

The attached photos show mine hanging out off the bottom. They can do that for hours. Excuse the algae, no longer have that. And these are quite old pics before i changed over to sand.

Perhaps bigger corys would work in your setup. They'd be a bit more bold and easier to feed. Pygmies are the only corys I've ever kept though, so don't know much about other species.

Check that your water parameters are suitable.
 

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What kind of gravel do you have?
There are pictures of it in the threads I linked, but here's another:

IMG_3596.jpegI would say the gravel is smaller than pea-sized.
All cories need a sand substrate so that would be my first step.
Perhaps change out the gravel and see how they recover before getting any more.
I came to the impression while researching before I got them (on this forum btw) that, while "cories need sand" is common aquarist knowledge, many cories in the wild live in rivers with gravel just like mine, and barbel injuries as a result of gravel usually happen because the aquarist is letting them "clean up" rather than providing their own sinking food. However, I have kinda desired lately to switch my gravel out for sand, because the bumpy gravel does still make it harder to feed them. I'm kinda kicking myself for considering it because I know it would be really hard to change out the whole substrate.
They do like to just chill on the substrate when they're resting so that on its own may not be a concern.
I know that they do that often even when they're happy, but I've been worried because the weaker spend long periods of time like this, and when they go back to the ground they don't swim over, they just kinda sink like they're pooped.
I think pygmies can be more interesting than larger cories as they go all over the water column not just the bottom, they may be more active etc if you add more.
That is something I hadn't considered! I did really enjoy the way they school around the tank.
They need a sedate tank. They can be a little skittish and I think with platies and zebra danios bumbling around they may be put off feeding and head for cover.
That is something I discussed on the other thread when I was first getting them. The plan originally was to rehome the danios (my platies ignore everything smaller than them for the most part), but, at least before there were so few of them, the cories didn't seem bothered by the danios at all in practice. For the first few days of having them, I would look at the tank and see my biggest (normally very grumpy) danio awkwardly edging away from a group of 4 well-meaning cories trying to investigate/school with him.


It's a new day and I've had a little more time to think. I do like my cories, but I wouldn't mind if I had a species with the same behavior but a little bigger and more eye-catching, especially if I knew they would be happier and healthier in my tank. I also failed to realize that my pygmys are not fully grown: mine are about 1/2 inch, and I mistakenly thought this was their mature size, but they actually get up to 1.2 inches, which is much closer to the size I'd prefer. I intend to watch some videos about Julii cories to see if I would like them, but I'm not completely set on replacing the pygmies yet, and I have more hope than I did yesterday that the species can do well in my tank if I get a larger group.
 
There are pictures of it in the threads I linked, but here's another:

View attachment 336490I would say the gravel is smaller than pea-sized.


I came to the impression while researching before I got them (on this forum btw) that, while "cories need sand" is common aquarist knowledge, many cories in the wild live in rivers with gravel just like mine, and barbel injuries as a result of gravel usually happen because the aquarist is letting them "clean up" rather than providing their own sinking food. However, I have kinda desired lately to switch my gravel out for sand, because the bumpy gravel does still make it harder to feed them. I'm kinda kicking myself for considering it because I know it would be really hard to change out the whole substrate.

I know that they do that often even when they're happy, but I've been worried because the weaker spend long periods of time like this, and when they go back to the ground they don't swim over, they just kinda sink like they're pooped.

That is something I hadn't considered! I did really enjoy the way they school around the tank.

That is something I discussed on the other thread when I was first getting them. The plan originally was to rehome the danios (my platies ignore everything smaller than them for the most part), but, at least before there were so few of them, the cories didn't seem bothered by the danios at all in practice. For the first few days of having them, I would look at the tank and see my biggest (normally very grumpy) danio awkwardly edging away from a group of 4 well-meaning cories trying to investigate/school with him.


It's a new day and I've had a little more time to think. I do like my cories, but I wouldn't mind if I had a species with the same behavior but a little bigger and more eye-catching, especially if I knew they would be happier and healthier in my tank. I also failed to realize that my pygmys are not fully grown: mine are about 1/2 inch, and I mistakenly thought this was their mature size, but they actually get up to 1.2 inches, which is much closer to the size I'd prefer. I intend to watch some videos about Julii cories to see if I would like them, but I'm not completely set on replacing the pygmies yet, and I have more hope than I did yesterday that the species can do well in my tank if I get a larger group.
You could always swap the substrate gradually, it's going to be a messy job either way, it's not something I've done so not sure what the best way to do it is!

I actually have some julii cories (not sure if they might be false juliis tbh, there are a few similar looking ones) and they are really shy compared to the pygmies. I also have pandas and they are less shy. I love the look of sterbais, I know you mentioned those before. I can only speak from my own limited experience but I find it interesting that the different varieties seem to have different personalities.
 
My experience with sterbai is that they're much shyer and more skittish than any other cory species I've kept (which isn't a huge variety yet, admittedly). I started with six sterbai, in a heavily planted tank, and they still super skittish and shy compared to the bumbling bronzes, and compared to a large group of pygmies. While they're visually striking, and commonly available, even once I decided to move them to a larger tank with my bronzes, since greater numbers usually means they feel more secure and happy to be out in the open, the sterbai remain much more shy than the others, and anecdotally, I've heard the same from others who've kept them. Corydoras aeneus (bronzes) seem to be the bumbling, friendly, labrador of the cory world, while sterbai I'd compare more to shy Italian Greyhounds or something.

In regards to cories and sand substrates, Ian Fuller, owner of Corydoras World has long been regarded as an internationally recognised expert in corydoras, and he stresses that while cories can be found living among a variety of substrates in the wild, they undeniably filter feed through sand, spitting the sand and unwanted items out through their gills as they filter through the substrate looking for food. He's recorded many videos of cories doing this.

Barbel erosion isn't the only issue with cories and gravel substrate, although it is absolutely a concern. But they're also unable to practice one of their natural behaviours - filter feeding - when kept on gravel alone. With pygmy corydoras, the sand substrate needs to be particularly fine, since they're so small.

While I encourage anyone to use critical thinking and always question the source, of course, I do find it strange when relatively newcomers think they know better than recognised authorities in a field, especially when that suits their own wishes.

But fish kept in the wrong numbers, on the wrong kind of substrate, with the wrong kind of fish, are absolutely not going to be showing at their best, let alone showing their full range of behaviours as they would in the wild, or in a more natural to them set up.


I wouldn't recommend a single panda garra, nor with the type of set up you have now - they have even more specialised behaviours and need a set up designed around their needs.
 
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Forgot to mention - bear in mind that while switching out substrate is absolutely do-able - that a large portion of your beneficial bacteria (BB) that convert the fish waste from ammonia to nitrites to nitrates, attach to hard surfaces in the tank and in the filter, they don't live in the water column, and the largest bed of bacteria is almost certainly within your substrate. So switching it out all at once can easily cause a mini cycle, or a tank crash, if unprepared.

It's entirely possible to work around it, but better to know in advance so you can prepare and avoid that, rather than switch it out one weekend and be surprised if problems arise.
 
Yeah, you need sand really. I think that platies and zebra danios are not a great match for pygmy corys, so that may be an issue. They need a sedate tank. They can be a little skittish and I think with platies and zebra danios bumbling around they may be put off feeding and head for cover. I keep mine with chilli rasboras and cherry shrimp. They compete well for food even though the cherry shrimp swarm around the food.

You need to use crushed flake food and/or micro granules. They also quite like microworms and fruitfly larvae. I'd recommend NT labs micro crumb or dennerle nanogran as staple granular food. I use a large catappa leaf as a serving tray. I mix the microgranules with a little tank water and then use a pipette to squirt the suspended granules down onto the leaf. The corys snuffle around the leaf hoovering up the granules. Sometimes they can be a little skittish and will give feeding a miss, but not very often.

They are perhaps a little drab in colour but as Lcc86 says, when they are settled they are active in mid water as well as the bottom, and whilst I never got any fry due to the shrimp eating the eggs, it was cool to watch them regularly swimming through the plants and depositing eggs on the leaves. They are also very cute in that sometimes two of them will go off on their own and find a little hollow in a piece of bogwood and use it as a resting place.

Sadly, I'm now down to my last two as the others have gradually died over the last 3 years. I am not going to get any more for now as I'd prefer to keep a larger school of chilli rasboras rather than limit the number of chillis to keep the corys.

They seem perfectly happy with just the two of them, although a larger group is recommended and will look far better.

The attached photos show mine hanging out off the bottom. They can do that for hours. Excuse the algae, no longer have that. And these are quite old pics before i changed over to sand.

Perhaps bigger corys would work in your setup. They'd be a bit more bold and easier to feed. Pygmies are the only corys I've ever kept though, so don't know much about other species.

Check that your water parameters are suitable.
How do you cultivate fruit fly larvae?
Mine love baby brine shrimp.
 
How do you cultivate fruit fly larvae?
Mine love baby brine shrimp.
It happened by accident at first when some fruit flies got into my micro worm culture and laid eggs. I didn’t notice until I scraped some microworms off the side of the container to feed my fish, and in amongst the microworms were some fruit fly larvae. So I then started to encourage it. I’d leave some over ripe fruit on the windowsill in the spring/summer and I’d place a microworm culture next to it. The fruit fly larvae seemed perfectly happy in amongst the microworms and they crawl up the side of the container so are easy to harvest. There’s probably a more efficient way of raising fruit fly larvae with a dedicated culture but it works for me.
 
I think my tank just isn't going to work with any kind of cories. I'm keeping them in an environment that's different from their natural one on a bunch of different points, and none of them are something I can easily change. I wish I had just used sand when I started the tank, but I don't think there's any way I could feasibly replace all the substrate (certainly not as a beginner) short of scrapping and rebuilding the entire tank from scratch. This is the only tank I have, so I can't just take all the fish out of it, and I certainly don't want to risk a cycle crash even if I do manage the rest of the process.
 
It happened by accident at first when some fruit flies got into my micro worm culture and laid eggs. I didn’t notice until I scraped some microworms off the side of the container to feed my fish, and in amongst the microworms were some fruit fly larvae. So I then started to encourage it. I’d leave some over ripe fruit on the windowsill in the spring/summer and I’d place a microworm culture next to it. The fruit fly larvae seemed perfectly happy in amongst the microworms and they crawl up the side of the container so are easy to harvest. There’s probably a more efficient way of raising fruit fly larvae with a dedicated culture but it works for me.
Now I'm wondering if this would work with a grindal worm culture... 🤔
I like feeding live foods to my fish. So far I've done BBS, mosquito larvae and grindal worms. I don't see the pygmys go for the latter two. Maybe they're too big. So I'm on the look out for more pygmy cory friendly live foods. I'll start a daphnia culture in the spring.
 
Although I would like to point out (only because I'm salty about all this right now) that I didn't just make up the stuff about them being fine with gravel, I heard it from @emeraldking on THIS forum. No one mentioned sand being crucial to their feeding when I had a whole long thread asking if they would be OK in my tank.
 
I wouldn't recommend a single panda garra, nor with the type of set up you have now - they have even more specialised behaviours and need a set up designed around their needs.
Please elaborate- I couldn't find many resources on them
 
Sand isn't needed for the three pygmy Cory species. They swim mid water, and have taken a different direction from their larger Genus mates. Sand really makes a difference with 'standard' Corys, but the tiny ones are exceptions.

I suspect all would be well if you had 10 in there. Add them before you treat the platys, so everyone gets dewormed.
 
Please elaborate- I couldn't find many resources on them

Seriously Fish is a reliable website for species specific info.

"Not difficult to keep in a well-maintained set-up, but a display arranged to resemble a flowing stream or river, with a substrate of variably-sized, water-worn rocks, sand, fine gravel and perhaps some small boulders, is highly recommended. This can be further furnished with driftwood roots or branches, and hardy aquatic plants such as Microsorum, Bolbitis, or Anubias spp., which can be grown attached to items of décor.

Most importantly, the water must be clean and well-oxygenated with turnover preferably in excess of 10 times per hour; additional powerheads and airstones can be employed to achieve the desired flow and oxygenation if necessary. Bright lighting will promote development of biofilm on solid surfaces, upon which the fish will graze.

Since it needs stable water conditions and grazes biofilm this species should never be added to a biologically immature set-up, and a tightly-fitting cover is necessary since it can literally climb glass."

@WhistlingBadger has an amazing youtube video somewhere of his group of panda garra climbing the glass because they were climbing up through the water output, they seem to thrive in those high flow, highly oxygenated streams, and their shape is a visual clu to the type of environments they've evolved to live in.

Also from Seriously Fish:

"Relatively peaceful and makes a good subject for the well-chosen, larger community of stream-dwelling Indochinese species.

It isn’t particularly tolerant of conspecifics but normally exists in loose aggregations in the wild. If kept singly it tends to behave more aggressively with similarly-shaped fishes so we recommend the purchase of 3-4 or more should space permit. Such a group will develop a noticeable pecking order between themselves but tankmates are more likely to be left alone. What appear to be hierarchical disputes will sometimes occur and involve charging, flaring of fins and an overall paling of the body colouration."

@JackGulley Try not to be discouraged. There's tons of fish in the hobby, lots to learn, and if nothing else, it teaches you patience! Things aren't all or nothing, terrible or perfect, catastrophe nor perfect.
 

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