Corydoras pygmaeus colony breeding, surprise!

AdoraBelle Dearheart

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I knew I wanted pygmy cories at some point, and wanted to try and breed them at a later date too, but none of it happened how I planned. Yet things turned out even better than I could have hoped? LOL. I could still do with some input and advice though, since I think the tank might be reaching overstocking levels and I'm going to need to catch and rehome some youngsters. I'm dreading the task of catching and sorting them though. You'll see why when you look at the photos.

Tank talk
This is the first tank I ever bought and set up for myself, and it's changed and evolved a lot since I started it about two years ago. I had planned to tear it down and either sell and replace it, or revamp it (all my tanks have to be moved soon, to accommodate a larger tank) since I know more now than as a complete beginner, and because I'd set it up with this pale gravel substrate, and I'm not keen on gravel anymore, particularly for cories.

This photo is from when I first set it up :lol: :blush: Bought second hand, it's a 60 litre/15.5 gallon AquaOne tank with a mismatched, ill-fitting hood. I set up the tank in June 2019, seeded cycle using media and substrate from my dad's long established tank, and this photo is dated from the end of August, 2019. It didn't take long for it to fully cycle, but took several attempts to find guppies that would survive longer than a week... almost made me quit right there. Stock and scape have changed many times since then.

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Here is how it looks today;

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Current stock is a few male guppies, the elderly and disabled ones left from when I was breeding livebearers (plus three young pretty males I couldn't bear to part with); three otocinclus, many MTS and annoying tiny pest ramshorn snails, and pygmy corydoras.

I hadn't planned to get pygmies yet, but I did something many of us have done, and impulse bought a singleton at the LFS because he was on his own, and I felt sorry for him. I let the store owners know I wanted another batch of them as soon as they could get some, and took him him home, figuring he'd at least have the company of the otos and guppies until I could get some more pygmy friends for him.

I couldn't empty the tank to replace the substrate totally since it was established and risky to switch it out, and the plan was to tear down and rebuild the tank at a later date anyway. So I added a fine sand beach at the front right. Made it into a feeding area as a temp measure until the big tank moves could go ahead. It took a long time to get some friends for him, some supplier problems meant neither LFS had them in stock for months, and when I looked online, the cost of shipping added to the cost of the fish was out of my budget range. So Larry (who turned out to be female, of course!) was full grown by the time I got another batch.

My LFS finally let me know they'd got some pygmies in, but they only had four available. I reserved all of them. When I went to collect, they only had one! Took him home anyway, and skipped quarantine since Larry had been alone for so long, I felt bad for him. The new one was so tiny compared to Larry! Only a baby really. Next I managed to get hold of six juveniles, all looked really healthy, also tiny, and added them too. I lost one of the new ones in the first week, so had seven pygmy cories total. I planned to get another batch when I could, wanting a school of about 12 in total, thinking it was a good amount for this size tank and cories are happier in big groups.

Breeding was the last thing on my mind. I was busy with life stuff, and my livebearers and bronze cories were producing more than enough babies! Since only one was an adult and the others were juveniles, I put the idea of breeding them to the back of my mind. Something I'd want to try as a long term plan, but not at this point. I also thought I would have to try to breed them; that I'd need to condition the adults, that the fry would need careful attention and raising. I never knew that they could take care of it themselves in a colony set up!

Just a couple of months ago, I think it was in May - I was feeding the tank and watching them eat, when a much smaller pygmy appeared! I couldn't believe that it was a baby, and a good sized baby at that... tiny compared to the adults, but it had it's adult colouring, not the stripes that very young fry have. So I knew it had to be several weeks old, and raised itself in the tank, without my knowing or doing anything extra to give tiny food or anything! I was over the moon, but also thought it was a lucky fluke. I've had a bronze cory baby appear in their tank once as well, an egg that I'd missed but had survived, the adults usually eat the eggs, and other fish would pick off the eggs and fry too. There were guppies with the pygmy cories, and I'd heard they are harder to breed than bronzes, so while I was so excited about this baby, I didn't really expect any others to make it.

The next time I did a gravel vac and W/C, I spooked another baby out of his hiding spot deep in the plant growth. Two babies! Then I'd see more and more.... and saw the adults spawning every few days - it seemed constant!

Now, I have no idea how many pygmies are in there. The fry hide all over the place, including down in the gravel at the back (makes substrate cleaning tricky), and under the slate cave that they prefer to sit beneath or on top of, rather than going inside;
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When I lift the slate cave, fry of varying sizes dart away everywhere. The adults just keep spawning! I cleaned the substrate two days ago and found a newborn fry, no more than two days old in the bucket.

I dropped an algae disc in here just to show this;
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Last time I tried to count, there were roughly 23 good sized ones in there, not counting fry; but it really is impossible to count, since while 23 might be out eating, another dozen could be chilling under leaves or hiding in the dense plants. They do seem to break into 3-4 smaller groups now and again, hanging in different areas of the tank, swimming together etc.
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When I first found tiny fry in there, I panicked about how I'd clean the substrate. Gravel holds so much muck; I use a lot of leaf litter/almond cones etc in there which leave a lot of detritus; fish poop falls down into the gravel; gravel isn't recommended for cories; potential for bacterial infections if the substrate isn't cleaned well; and the tiny, insect-like fry are incredibly hard to spot when they're hidden among all that mulm and plant matter at the bottom of a bucket. Also impossible to avoid sucking them up. Have seen babies burying themselves in the gravel when spooked.

On the other hand - when I W/C this tank, I can see seed shrimp and other tiny micro-organisms swimming in the water and muck I've removed. Stuff I don't see when W/Cing my other two tanks. I suspect the fry have been largely living on those, and mulm itself is harmless, right? I love @AbbeysDad 's article on algae, mulm and snails, and I hope that those three things are balanced well in my tank at the moment. The plants are also thriving in the gravel, while I suspect that the roots might be too compacted in fine sand, and not have that mulm and detritus the plants can get from the gravel.

But the pygmies undoubtedly enjoy feeding from and playing in the sand, and often just sitting on the sand section in little groups, looking as though they're having a day at the beach.

I wonder if I have the best of both worlds right now, and I hesitate to tear down an ecosystem that's working for them. I'm tempted to move a batch of the adults to my other, sand only tank and see how they do there, if they will keep spawning the fry have just a good a success rate there. I'm torn on the substrate issue... I know that many people here feel strongly about sand vs gravel, and cories on sand or not. I'd love more feedback, scientific links, personal experiences and advice - anything people would like to contribute or share, if done respectfully of course.
 
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AdoraBelle Dearheart

AdoraBelle Dearheart

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Cories look like rabbits (forever twitching noses) and breed like rabbits....the true bunnywunnies of an aquarium ;)
They do!! When they hover in the water, tiny fins going like mad but those big dark eyes watching you, waiting to see if they need to dive for cover - they really are similar to rabbits in a field frozen with their head up, checking for danger before diving for cover! I hadn't thought of the bunny comparison, but it really does fit them.

They do spook pretty easily too. So many little eyes watching, and if one spooks, they all do! Makes it even harder to get a headcount. At least they calm down fast and start emerging from hiding again, once they know you're not a threat. I've learned to sneak up slowly and watch from a bit of distance :D
 

wasmewasntit

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I have a pair of Cory desperately trying to "get jiggy with it"....frantic egg laying on the glass....BN spies it, flies up the glass and munches them....Cory pair throwing indignant looks at BN.....once BN has finished, Cory pair go replace the eggs again

This has been going on nonstop now for the last 3 days :D

Stubborn determination.
 
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AdoraBelle Dearheart

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Accidentally posted too soon, have edited OP to include the main point of the thread! LOL.
 
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AdoraBelle Dearheart

AdoraBelle Dearheart

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I have a pair of Cory desperately trying to "get jiggy with it"....frantic egg laying on the glass....BN spies it, flies up the glass and munches them....Cory pair throwing indignant looks at BN.....once BN has finished, Cory pair go replace the eggs again

This has been going on nonstop now for the last 3 days :D

Stubborn determination.
Haha, cute! What species of cory?
 

Lajos_Detari

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Congratulations!
Will you be inviting us for their 1 month birthday? Lol

There was one elderly man who used to work in my office.
Then one day he became interested in keeping shrimps after I showed him my shrimps tank.
After keeping the shrimps for about 2weeks, his shrimps started to give birth.
He was excited and he showed us his shrimplets to us....
My colleagues congratulated him for becoming a "grandfather"...Lol
And we asked him whether he will be inviting us for the birth of his "granchildren"...

Anyway, just for jokes...

:banana:
 

Bruce Leyland-Jones

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I love these little fish...nearly always active, bold enough to check every other fish in the tank out and sociable enough to either shoal, school or just mess about on their own.
Congrats on your success with such a small tank and I'm also in the gravel AND sand camp. ;)
 
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AdoraBelle Dearheart

AdoraBelle Dearheart

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I love these little fish...nearly always active, bold enough to check every other fish in the tank out and sociable enough to either shoal, school or just mess about on their own.
Congrats on your success with such a small tank and I'm also in the gravel AND sand camp. ;)

Thank you! Completely agree with how wonderful these little fish are, especially in larger groups! I'm desperate to try getting some habrosus now and have them colony breeding in another tank. :D I have to patient though, lots of other things have to get sorted before I can do that.

I've been loving watching them ever since I only had Larry. Seeing one kept alone for so long, and the difference in their behaviour when in a decent sized group really bought it home to me how sociable cories are and that they need a group to thrive. I knew that already, of course, but seeing the difference with your own eyes really brings it home. I love watching them in the group of 20 odd they have now (and seeing more and more join them!) they're so active, adorable and fascinating to watch interact. The otos work well with them too, and are often found sitting in the same place as the cories. Finding new fry all the time is wonderful, but a tad overwhelming how rapidly it went from spotting two babies in May, to having at least 23 adults and sub-adults everywhere! With more coming all the time...

It's a self-continuing cycle though! I do once or twice weekly water changes of roughly 50-60%, and use Bug Bites and a good deal of live and frozen food in here. Live microworms, and tiny frozen things like cyclops and dahnia - wanting to be sure that there's enough small food for the tiny freshly hatched fry (which almost look like insects when first hatched, they're so tiny!); but that also keeps the adults in breeding condition all the time! Not complaining, I hasten to add! Just dreading having to catch and find a home for youngsters since I don't want to overstock the tank, and catching them in a well-planted tank won't be easy! How am I going to manage it?! LOL.
 
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AdoraBelle Dearheart

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Congratulations!
Will you be inviting us for their 1 month birthday? Lol

There was one elderly man who used to work in my office.
Then one day he became interested in keeping shrimps after I showed him my shrimps tank.
After keeping the shrimps for about 2weeks, his shrimps started to give birth.
He was excited and he showed us his shrimplets to us....
My colleagues congratulated him for becoming a "grandfather"...Lol
And we asked him whether he will be inviting us for the birth of his "granchildren"...

Anyway, just for jokes...

:banana:

:lol: I don't blame him! It's so exciting when shrimp start breeding! It took me months to get my first shrimplets when I first got shrimp; jealous he managed to have baby shrimp so quickly! :lol:;) And it's excited when it happens! I'm still happy whenever I spotted a berried female.

You are all always welcome to their birthday celebrations too! :-:drinks:

On a serious note though, @Lajos_Detari , I know that you know a lot about planted tanks/shrimp/substrate, have a lot of experience and do proper research - I'd love to hear your thoughts on what I should do regarding the substrate!

I will always have fine sand for the cories, but I'm sorta liking having both sand AND gravel in this tank. It does make cleaning and maintaining the tank a bit harder, but as I said in OP, I am wondering if the gravel is actually helping me out here in a way a sand only tank may not? Have heard and read things about plant roots doing better in a fine or pea gravel than they would in fine sand, and obviously it allows mulm to build and nutrients to circulate in a way they cannot with fine sand(?).

In this tank the gravel is basically pushed to the back third of the tank, with some on the left front too. The large rooted plants are back there in the gravel - vallis, l.sessiliflra, siamensis 53B, and the largest crypts are all in the gravel, and I can't imagine them holding secure and thriving as well in sand - or would they? I've seen @seangee's @mbsqw1d's and @Byron's stunning planted tanks where the plants are amazing, and I know they have sand only substrate!

I have seen so many arguments for either side, and conflicting advice at other places online, of course! That I'm massively confused, and conflicted about whether I should leave the tank as it is since it's working - or if I should be tearing it down and making it sand only.

I'm firm in my opinion that cories benefit from digging through and filter feeding with sand; I've seen them do it with my own eyes. But along with personally enjoying the natural look of mixed substrates, I'm also wondering about the benefits of gravel in terms of mulm and micro-organisms. That I only see seed shrimp and other tiny swimming free fish food in the water from this tank, and not my others despite the same sort of feeding... But on the other hand, I don't want to risk my pygmies being harmed by rooting through gravel! Have seen @Colin_T and @Byron (both of whom I respect hugely) talk about gravel increasing the risk of nasty bacteria lurking, and bacterial infections for cories kept on gravel. But then I have just as much respect for @AbbeysDad's experience and science based knowledge; and his article about mulm, algae and snails is something I've kept in mind since I first got this tank, and the mulm does seem to promote the micro-organisms in there.

Is avoiding the nasty bacteria and risks to cories just a case of careful maintenance? Gravel vac-ing gravel more thoroughly and being wary of stagnant pockets, but also not being too scared of mulm and over cleaning? That's what I've always aimed for in this tank. I don't see mulm at all in my tank that only has black limpopo sand.

I'd also really appreciate hearing other people's experiences/thoughts/articles/advice from more experienced and knowledgeable folks, if they have anything they're happy to share! No pressure, and I don't want to cause arguments or heated debates either... I know many folks feel strongly about this topic and it's caused fights before. :/ I don't want to cause that :S I'm just genuinely conflicted and confused, and want to learn more, especially before I have to move the tank and make the decision whether to keep it as is or not.

Tagging some people who I know are into planted tanks/talking substrate in hopes of learning more, but no pressure on any of you to reply! Anyone else I haven't tagged is also more than welcome to share too of course!

@Byron @Ch4rlie @mbsqw1d @seangee @itiwhetu @Colin_T @Bruce Leyland-Jones @Naughts @WhistlingBadger @Wills
 

Byron

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I will always have fine sand for the cories, but I'm sorta liking having both sand AND gravel in this tank. It does make cleaning and maintaining the tank a bit harder, but as I said in OP, I am wondering if the gravel is actually helping me out here in a way a sand only tank may not? Have heard and read things about plant roots doing better in a fine or pea gravel than they would in fine sand, and obviously it allows mulm to build and nutrients to circulate in a way they cannot with fine sand(?).

In this tank the gravel is basically pushed to the back third of the tank, with some on the left front too. The large rooted plants are back there in the gravel - vallis, l.sessiliflra, siamensis 53B, and the largest crypts are all in the gravel, and I can't imagine them holding secure and thriving as well in sand - or would they? I've seen @seangee's @mbsqw1d's and @Byron's stunning planted tanks where the plants are amazing, and I know they have sand only substrate!

I would not mess with what you have now. I see no problems for the cories, nor the plants. The area of sand at the front right obviously serves the cories...in your photos this is where they are, not surprising at all. But they will browse every surface including the gravel, wood, plant leaves, right up to the surface. I would put the cory food in the sand patch, always. This allows them to naturally feed by filtering through it.

There are mixed substance substrates (beside just sand) in some cory habitats; not that of this species which is endemic to the Rio Madeira system in western Brazil, so far as I know, but that doesn't matter. Sand is essential for all cories because of their feeding method. I'll comment on the bacterial issue below. The sand patch here is fine.

I'm firm in my opinion that cories benefit from digging through and filter feeding with sand; I've seen them do it with my own eyes. But along with personally enjoying the natural look of mixed substrates, I'm also wondering about the benefits of gravel in terms of mulm and micro-organisms. That I only see seed shrimp and other tiny swimming free fish food in the water from this tank, and not my others despite the same sort of feeding... But on the other hand, I don't want to risk my pygmies being harmed by rooting through gravel! Have seen @Colin_T and @Byron (both of whom I respect hugely) talk about gravel increasing the risk of nasty bacteria lurking, and bacterial infections for cories kept on gravel. But then I have just as much respect for @AbbeysDad's experience and science based knowledge; and his article about mulm, algae and snails is something I've kept in mind since I first got this tank, and the mulm does seem to promote the micro-organisms in there.

Is avoiding the nasty bacteria and risks to cories just a case of careful maintenance? Gravel vac-ing gravel more thoroughly and being wary of stagnant pockets, but also not being too scared of mulm and over cleaning? That's what I've always aimed for in this tank. I don't see mulm at all in my tank that only has black limpopo sand.

The problem with gravel that is too large, and obviously also with pebbles, is that food bits get down among the grains where the cories cannot get them like they can in sand. The food decomposes differently than it would in sand (or if eaten!) and bacterial issues can often result for substrate fish. The mix of materials that includes sand should be OK to avoid this issue. But yes, if you can get to the gravel areas during the water change, definitely give these areas a good vacuum. This is not normally necessary with sand (your comment on the black sand is just what I would expect), but if you seem mulm appearing do a vacuum with the W/C just above the surface; it is easy to work out how to do this without sucking up sand. Not overfeeding should avoid sand issues.
 
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AdoraBelle Dearheart

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I would not mess with what you have now. I see no problems for the cories, nor the plants. The area of sand at the front right obviously serves the cories...in your photos this is where they are, not surprising at all. But they will browse every surface including the gravel, wood, plant leaves, right up to the surface. I would put the cory food in the sand patch, always. This allows them to naturally feed by filtering through it.

There are mixed substance substrates (beside just sand) in some cory habitats; not that of this species which is endemic to the Rio Madeira system in western Brazil, so far as I know, but that doesn't matter. Sand is essential for all cories because of their feeding method. I'll comment on the bacterial issue below. The sand patch here is fine.



The problem with gravel that is too large, and obviously also with pebbles, is that food bits get down among the grains where the cories cannot get them like they can in sand. The food decomposes differently than it would in sand (or if eaten!) and bacterial issues can often result for substrate fish. The mix of materials that includes sand should be OK to avoid this issue. But yes, if you can get to the gravel areas during the water change, definitely give these areas a good vacuum. This is not normally necessary with sand (your comment on the black sand is just what I would expect), but if you seem mulm appearing do a vacuum with the W/C just above the surface; it is easy to work out how to do this without sucking up sand. Not overfeeding should avoid sand issues.

Have I told you lately how brilliant and helpful you are? Thank you so much!

Really happy that you don't see any issues with the cories or plants! Having the mixed substrate definitely means more time and effort to keep it clean, but I enjoy doing it. Gives me a chance to really get in there and see what's going on, in a way I don't really need to do in the sand only tank. I do always drop food like the Bug bites or veggies over the sand area; but of course things like the frozen daphnia float in the water column and wind up everywhere! The cories and (guppies) do pick at everything to eat it, working over the leaves, stones and gravel too. In the photos above, I dropped an algae wafer on the sand part because I knew that most of the pygmies would go wild for it and gather together for the photos :grr: :D but yes, they definitely do use the whole tank! Hanging near/on the sponge filter, huddling in groups under almond leaves if spooked, or under/in a dense planting area, or just sitting around on the sand/under plants/on the slate cave and on top of the log; and schooling in a big group mid-water, darting to the surface now and then for a gulp of air. Makes them so entertaining to watch!

The water parameters remain really stable, with the nitrates rarely going above 10ppm. I guess since it's a long established tank (two years), the plants suck up all the waste, and pygmies seem to have a pretty light bioload, as do otos. I have both a double sponge filter (with compartments of ceramic rings) and a HOB on there. The eight retired male guppies help to clean up any food on the substrate, as do the snails! While the pest ramshorns annoy me when the population explodes, they do signal to me that I'm overfeeding and need to cut that back and do a thorough cleaning. The MTS help keep everything turned and also clean up uneaten food.

I have a very small gravel vac that is perfect for working around the dense planting, and the livebearers and shrimplets trained me well to develop a system for hunting out any tiny babies that were syphoned up and need rescuing from the buckets of water I remove before I throw the water out! :lol: it means carefully going through it one jug at a time, then using a turkey baster to check the mulm and detritus for the almost invisible and perfectly camoflaged fry... takes ages and can be such a pain, but it's worth it to me.

Do you have a rough suggestion for how many adult pygmies this tank can support? I had thought about 12, but it's easily handling this 23 or so right now, only needing a WC once a week - it could go fortnightly or more without nitrates rising above 20ppm, but I've never tried leaving it longer. Obviously the cories like to be in as large a group as possible. Should I be guided by how stable the tank remains and how crowded it looks? I don't think I'd want more than 22 or so in there (not counting fry/small babies), but since it's working still at this stocking level (and I'm on top of plants/filtration/water changes 1-2 times a week), would I be overstocking it?

That would be a stocking level of;
8 guppies
3 otocinclus
22 adult pygmies plus fry and sub-adults until old enough to rehome.

In a 'normal' 60 litre/15.5 g, I'd consider that well-stocked, but perhaps a tad overstocked?
 

Ch4rlie

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I personally would not change too much in that tank of yours tbh, it’s obviously thriving and the cories seem happy with the blend of substrate that you have set up so best left alone I think.

Mulm is good for planted tanks as it’s full of good nutrients for plants and won’t do any harm to your livestock provided is mostly left alone.

So you have a really nice tank set up that works and obviously having Cory fry, you are doing things right, don’t try to fix something that’s not broken if that makes sense. sometime by fiddling drastically with things can alter thing massively and the fine ecosystem balance that’s in that tank may change for the worse.

Change things as minimal as possible so as not to upset the set up and be proud of that tank, show it off as much as you can!

You have bragging rights in being able to breed pygmys which incidentally are one of my favourite specie of cory ;)
 

Naughts

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I second Charlie's notion that if it ain't broke, don't fix it.

My plants include vals, crypts and hygrophila and they don't mind the fine sand so that wouldn't be a concern for me.
If you get to the point that you feel it is overstocked, why not move the guppies out?

And why the heck isn't this in TOTM?! 3 slots/ 1 day left to enter...;)
 

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