Corydoras Spawning media experiment

[KentFishFanUK]

Ok so I know many corydoras lay eggs on glass and other people will probably use spawning mops so this won't be of use to many other than myself but might be interesting anyway! 

So recently I've observed a few interesting things with my panda corydoras in my community tank. There is always breeding activity going on and eggs being laid but no fry appearing without pulling the eggs. My pandas never lay eggs on the glass, they occasionally lay eggs on roots of pothos hanging in the tank but mostly they use the java moss.

At one point I had a small tuft of black beard algae (like maybe less than an inch in diameter/length) right next to my java moss and one day I noticed eggs in it from the corydoras, more than I had ever seen in the java moss at one time and in a much smaller area (I found at least 6 eggs in that small tuft of BBA). Now I know most fish hate the taste of BBA so I assumed it was just because the taste protected the eggs from being eaten by the other fish or snails etc and that's why it appeared that way - a survivorship bias so to speak, rather than the corydoras specifically preferring it to the java moss. The small tuft died off after a little while and I've not had any since and haven't thought much on it. 

Then even more recently I had a but of a filamentous/blanket weed type algae bloom and I was being lax with removing it (my tanks are hardly designer aquascapes so I pretty much don't mind a bit of algae unless it seems to be causing problems with the plants) and there was a good bush of it going, maybe 6 inches long by a couple inches wide suspended across some plant leaves. One morning I turned the light on to discover it absolutely full of corydoras eggs, I think I counted at least 15 which is more than I've ever seen my cories lay at one time (I only have two females and four males). I have no idea if the 'spawning media' triggered more spawning than usual, or somehow protected the eggs from being eaten (not sure how as you can see right through it much easier than the java moss) or if it was simply a coincidence. 

So anyway my plan to experiment is to cultivate a bunch of blanket weed type algae in a spare tank, then DIY some sort of mop with it (I was thinking a small plastic Tupperware container full of the stuff) and put it in my community tank and see what happens. My hope is to find out if;

a) the corydoras do actually prefer it as a spawning media and it wasn't just a fluke 

b) this 'media' is somehow useful in protecting the eggs from the rest of the community

c) if having their preferred choice of spawning media actually encourages/triggers more spawning than would have occured otherwise (not sure how I will really determine this part)

Any thoughts or tips/advice?

Not sure how to contain the blanket weed in the container without restricting access but hopefully it will just sort of stay put. 

 

 

 

 

 

[Guppysnail]

I can’t give you much more than you already stated. My pandas far prefer the filament green hair algae. That is where I find most eggs and they are usually twisted up in it. 
My guesses were protection from fish predating, keeps nutrients down immediately around the egg so less chance of fungus etc. micro fauna live in the algae that, like shrimp, clean the eggs and keep fungus at bay. 
All guesses as I have seen the same as you. 
I find the micro fauna living in algae to be great fry food. I just let it grow. When the clumps get big I pull them out. It has never taken over a tank for and always stays manageable for me. 
 

[KentFishFanUK]

On 6/5/2022 at 12:56 AM, Guppysnail said:

I can’t give you much more than you already stated. My pandas far prefer the filament green hair algae. That is where I find most eggs and they are usually twisted up in it. 
My guesses were protection from fish predating, keeps nutrients down immediately around the egg so less chance of fungus etc. micro fauna live in the algae that, like shrimp, clean the eggs and keep fungus at bay. 
All guesses as I have seen the same as you. 
I find the micro fauna living in algae to be great fry food. I just let it grow. When the clumps get big I pull them out. It has never taken over a tank for and always stays manageable for me. 
 

Amazing thanks! Glad to know you've had the same experience. I find it super interesting and I've googled a bunch about breeding corydoras and pandas in particular and have never seen it mentioned before. 

Do you think that the pandas are just choosing it as a spawning site or do you think that having their preferred spawning site triggers more egg laying? 

The algae seems to grow quite well in my water so I will see if I can find a way to use it but keeping it contained so I can easily pull it to try and hatch the eggs in a separate container. 

The last batch of eggs I pulled I picked them out of most of the algae as I was worried that when they hatch they might get stuck in it, do you think it would be better to just leave them in it? 

[Guppysnail]

On 6/5/2022 at 3:47 AM, KentFishFanUK said:

they might get stuck

I thought this as well. I have not had the chance to pull any algae laid eggs yet so I don’t know. Im hoping instinct causes them to do this for whatever reason and it provides the fry whatever they need. Im hoping it’s the micro fauna first food and protection thing and they don’t get stuck but often the eggs get twisted up in from the current. I am just not certain if letting them in the algae is better. A few days ago I was able to move the pleco out of that tank that kept eating all the eggs. 

Honestly I’m as curious as you about this.

When mine were in with my guppies in a tank with almost no algae because the guppies eat it they would lay eggs on the glass  

Since they are in their own tank now that grows algae and has a good amount of low ground plants vs. none in the guppy tank, I have only ever seen eggs on glass maybe 5 eggs total. I mentioned in my journal somewhere when they first started to spawn in their new tank I thought it curious they did not lay their eggs on glass. 
I have only had my pandas about a year so I’m still learning about their behaviors. 
 

Very cool to have someone to bounce theories off of on this odd seeming behavior. 
 

[nabokovfan87]

On 6/4/2022 at 5:50 AM, KentFishFanUK said:

Any thoughts or tips/advice?

I have two pretty good size pieces of mopani in my tank.  The pandas have been with these pretty much ever since I've owned them.  It was kept in a tub with a light on and far too many nitrates because I just couldn't do WCs.  When I was able to move the fish out of the tub into the tank on dresser for winter the hardscape was decimated with BBA algae.  It was so bad to the point where I was basically scrubbing it as hard as I could and it just laughed at me.  I've since developed slightly better techniques to handle it and I am trying to reduce the hold this algae has on my hardscape and anubias. 

That being said for context, here has been my experience.

My black corys don't use mops and I have never gotten them to reliably spawn.  They did spawn once and it was near 100 eggs.  Out of that spawn I managed to have 2 fry survive.  (I now have the things on hand to pull eggs into a tumbler / breeder box). 

My pandas were in a 29G tank with Seiryu stone.  I started with a few more, but after acclimation I ended up with 3 and now I have 25+.  I got some variety of moss, not java moss, and I used that on my seiryu stone and that was the catalyst for them to spawn.  I wasn't trying to spawn them, but I have seen eggs on the underside of these big pieces of mopani. I've seen them on the moss itself as well as on the glass.  I can't be certain but I am pretty sure I have offered these pandas mops and they didn't use it either.  There is a lot that goes into it, like the color of the moss itself.

I do see them in the roots of anubias like you've described and I do see them in big bushes of plants trying to lay eggs.  The big takeaway for me is that pandas just want their eggs hidden. They want to try to protect them from predators and they simply are trying to find a place where they have a good chance of survival.  I wonder if this algae spot you've mentioned is simply better protected than other spots in the tank.

On 6/5/2022 at 12:47 AM, KentFishFanUK said:

Do you think that the pandas are just choosing it as a spawning site or do you think that having their preferred spawning site triggers more egg laying? 

I definitely think they "prefer" some surfaces over others.  It might be the right texture, but not the right texture in the right place too.  They can be pretty picky in my experience. I try to keep "things I know they like" in the tank and once they do use it, then I check it every so often or I will see a fry one night.  In the same tank, they would lay eggs on PSO once it went crazy and was the right size to hide the eggs enough.

One example of this, I have a really nice red lava rock that had a big bushel of anubias inside of it and it made this little cove for them to lay in.  They do enjoy the bottom of anubias leaves, but because these leaves were in the corner of a tank and protected, they loved to lay on those leaves in that spot.

On 6/5/2022 at 3:06 AM, Guppysnail said:

When mine were in with my guppies in a tank with almost no algae because the guppies eat it they would lay eggs on the glass

I'm at this point too 😕 I don't know if I should scrape certain parts of the tank to give them a clean surface or not. 

[KentFishFanUK]

On 6/6/2022 at 12:44 AM, nabokovfan87 said:

I have two pretty good size pieces of mopani in my tank.  The pandas have been with these pretty much ever since I've owned them.  It was kept in a tub with a light on and far too many nitrates because I just couldn't do WCs.  When I was able to move the fish out of the tub into the tank on dresser for winter the hardscape was decimated with BBA algae.  It was so bad to the point where I was basically scrubbing it as hard as I could and it just laughed at me.  I've since developed slightly better techniques to handle it and I am trying to reduce the hold this algae has on my hardscape and anubias. 

That being said for context, here has been my experience.

My black corys don't use mops and I have never gotten them to reliably spawn.  They did spawn once and it was near 100 eggs.  Out of that spawn I managed to have 2 fry survive.  (I now have the things on hand to pull eggs into a tumbler / breeder box). 

My pandas were in a 29G tank with Seiryu stone.  I started with a few more, but after acclimation I ended up with 3 and now I have 25+.  I got some variety of moss, not java moss, and I used that on my seiryu stone and that was the catalyst for them to spawn.  I wasn't trying to spawn them, but I have seen eggs on the underside of these big pieces of mopani. I've seen them on the moss itself as well as on the glass.  I can't be certain but I am pretty sure I have offered these pandas mops and they didn't use it either.  There is a lot that goes into it, like the color of the moss itself.

I do see them in the roots of anubias like you've described and I do see them in big bushes of plants trying to lay eggs.  The big takeaway for me is that pandas just want their eggs hidden. They want to try to protect them from predators and they simply are trying to find a place where they have a good chance of survival.  I wonder if this algae spot you've mentioned is simply better protected than other spots in the tank.

I definitely think they "prefer" some surfaces over others.  It might be the right texture, but not the right texture in the right place too.  They can be pretty picky in my experience. I try to keep "things I know they like" in the tank and once they do use it, then I check it every so often or I will see a fry one night.  In the same tank, they would lay eggs on PSO once it went crazy and was the right size to hide the eggs enough.

One example of this, I have a really nice red lava rock that had a big bushel of anubias inside of it and it made this little cove for them to lay in.  They do enjoy the bottom of anubias leaves, but because these leaves were in the corner of a tank and protected, they loved to lay on those leaves in that spot.

I'm at this point too 😕 I don't know if I should scrape certain parts of the tank to give them a clean surface or not. 

I don't think the spot the algae was in was more protected, it was way more in the open and right under the light than the java moss is, completely exposed to the open area my neon tetras hang out suspended across some PSO leaves - but there may be something about the algae itself that protects them, maybe the other fish don't like swimming through it? Also I have a bit of a.... let's say 'healthy' pink ramshorn snail population 🤣 and I'm pretty sure they eat the eggs too, maybe being suspended like it was (rather than on the substrate or something) kept it up and away from the snails and maybe the pandas instinctively know this?

I might have to not only try diy-ing some sort of algae mop but also try a few in different areas of the tank and see if that makes much difference? 

[nabokovfan87]

Definitely interesting! I look forward to seeing what you uncover.

[KentFishFanUK]

On 6/5/2022 at 11:06 AM, Guppysnail said:

I thought this as well. I have not had the chance to pull any algae laid eggs yet so I don’t know. Im hoping instinct causes them to do this for whatever reason and it provides the fry whatever they need. Im hoping it’s the micro fauna first food and protection thing and they don’t get stuck but often the eggs get twisted up in from the current. I am just not certain if letting them in the algae is better. A few days ago I was able to move the pleco out of that tank that kept eating all the eggs. 

Honestly I’m as curious as you about this.

When mine were in with my guppies in a tank with almost no algae because the guppies eat it they would lay eggs on the glass  

Since they are in their own tank now that grows algae and has a good amount of low ground plants vs. none in the guppy tank, I have only ever seen eggs on glass maybe 5 eggs total. I mentioned in my journal somewhere when they first started to spawn in their new tank I thought it curious they did not lay their eggs on glass. 
I have only had my pandas about a year so I’m still learning about their behaviors. 
 

Very cool to have someone to bounce theories off of on this odd seeming behavior. 
 

Agreed! When I manage to test it out I'll be  post back here with some pics and the results! 

Its a fun experiment anyway. Plus I just love my pandas, I think they might be my favourite fish haha. 

Side note, that batch of eggs I pulled has now mostly hatched! When do I start feeding them? Is the little 'bubble' looking thing on them the yolk sac? 

[Guppysnail]

@KentFishFanUK it’s interesting you bring up the snails eating so the pandas may be suspending the eggs. I find the eggs on single strands of hair algae floating in the middle of the tank as well. My BN pleco was eating them off leaves. There might be something to that. I put lots on anubias in that tank so they would have large flat leaves to lay on and seldom see eggs on them. Instead I also find eggs on my anacharis leaves which are small but tall and flowing in the current. 
 

The few I have found on the glass are always in spots where there is either diatom or green spot algae.  

[KentFishFanUK]

On 6/6/2022 at 10:46 AM, Guppysnail said:

@KentFishFanUK it’s interesting you bring up the snails eating so the pandas may be suspending the eggs. I find the eggs on single strands of hair algae floating in the middle of the tank as well. My BN pleco was eating them off leaves. There might be something to that. I put lots on anubias in that tank so they would have large flat leaves to lay on and seldom see eggs on them. Instead I also find eggs on my anacharis leaves which are small but tall and flowing in the current. 
 

The few I have found on the glass are always in spots where there is either diatom or green spot algae.  

Same I've never seen eggs on driftwood, crpyts, anubias, java ferns only on java moss, BBA, thread algae and on the mass of pothos roots hanging into the tank - though this only before I added the java moss and had any of those algae's showing up. 

So you'd think spawning mops would be attractive to them if they are green and suspended but @nabokovfan87 didn't get any spawning on his mops. So maybe it's a location and texture thing combined? 

The location of my thread algae looks to me to be much more exposed (to like the tetras etc) but maybe the pandas in the wild live mostly alongside other benthic fish and less pelagic(?) ones? Maybe someone with more knowledge on fishes distribution could answer haha which could explain why they like to suspend the eggs away from the floor/broad leaves of plants

[Guppysnail]

On 6/5/2022 at 7:44 PM, nabokovfan87 said:

y black corys don't use mops

Thanks this just reminded me I bought a pool noodle and scotch bright pads to make one of Deans floating spawning mops to try and simulate the anacharis floating for them to spawn on. I totally forgot because I have so many projects going on right now. I ordered one that showed a green pool noodle and got a blue one that’s why I did not do it right away. I was worried the blue would cause the pandas issue. 
 

On 6/6/2022 at 5:46 AM, Guppysnail said:

The few I have found on the glass are always in spots where there is either diatom or green spot algae.

I’m not certain. The ones I pulled hatched but they did not make it past the egg sac still being absorbed. I had them in breeder boxes. Based on a few things I read I think even the small flow was to much for them. I also did not have plants in the box and it was sterile because I just got it so lacked micro fauna and biofilm first foods that I think might be essential. 
 

I found one tiny fry that was almost done absorbing the egg sac in the parent tank when the pleco was still in there.  I accidentally sucked it up in the python because I had seen no eggs in 2 weeks so thought I was safe to vac.  The interesting thing was when I pinched the hose to let the fry back out it dove into and under the gravel. I have cheap big box gravel. My next attempt is going to be a floating coffee filter @TheDukeAnumber1 shared. I already have the styrofoam that it sits in. I want it to float in my ugly fry tank so when they hatch and the egg sac is absorbed if they don’t eat I can release them to them gravel. I did just pick up a micro worm culture so I’m hoping that helps stimulate them. The few that hatched for me were to small for BBS. 
I had also bought some Java moss for my shrimp (I hate Java moss) to throw in the breeder box.  

On 6/6/2022 at 6:05 AM, KentFishFanUK said:

location and texture thing combined? 

 

Yes I was thinking location. Mine lay in the flow and texture is why I went with Deans scrub pad floating mop. So it would look and sort of feel like a rough algae and be floating. 

[Guppysnail]

Oh and I was going to turn the scrub pad longways so it trails further into the tank like the anacharis. 

[Guppysnail]

Oh and yes the bubble is the yolk sac. 

[KentFishFanUK]

On 6/6/2022 at 11:07 AM, Guppysnail said:

Thanks this just reminded me I bought a pool noodle and scotch bright pads to make one of Deans floating spawning mops to try and simulate the anacharis floating for them to spawn on. I totally forgot because I have so many projects going on right now. I ordered one that showed a green pool noodle and got a blue one that’s why I did not do it right away. I was worried the blue would cause the pandas issue. 
 

I’m not certain. The ones I pulled hatched but they did not make it past the egg sac still being absorbed. I had them in breeder boxes. Based on a few things I read I think even the small flow was to much for them. I also did not have plants in the box and it was sterile because I just got it so lacked micro fauna and biofilm first foods that I think might be essential. 
 

I found one tiny fry that was almost done absorbing the egg sac in the parent tank when the pleco was still in there.  I accidentally sucked it up in the python because I had seen no eggs in 2 weeks so thought I was safe to vac.  The interesting thing was when I pinched the hose to let the fry back out it dove into and under the gravel. I have cheap big box gravel. My next attempt is going to be a floating coffee filter @TheDukeAnumber1 shared. I already have the styrofoam that it sits in. I want it to float in my ugly fry tank so when they hatch and the egg sac is absorbed if they don’t eat I can release them to them gravel. I did just pick up a micro worm culture so I’m hoping that helps stimulate them. The few that hatched for me were to small for BBS. 
I had also bought some Java moss for my shrimp (I hate Java moss) to throw in the breeder box.  

Keep us posted! 

I've not had any success past getting them to hatch either, except one - I pulled maybe 4 or 5 eggs a little while ago and wasn't sure what to do with them (my breeder box attempts were fails) so just chucked them into a 3 gallon tank that was quite established that I was mostly using to hold/grow out some plants (I don't like throwing trimmings away 😅) and didn't think any had made it but then randomly saw a super cute little fry in there a few days ago, probably half an inch long maybe slightly more and not really Cory shaped yet but does have the black band across its face already! Not sure what size it would be safe to add it back to my display tank with its parents though?

The eggs I pulled recently which have just hatched are in a plastic jug that I normally use for water changes haha but with some moss and a whole lot of infusoria so once I know they are all hatched I'm going to pour them into the plant tank and hopefully some will make it. Might have to reduce the bubbles on the sponge filter if they don't like flow. There also happens to be quite a lot of thread algae in there which I will remove a bit of but leave a bunch too. Fingers crossed!

I do have a vinegar eel culture which I've been using to feed ricefish fry that I will probably feed to the panda fry too as though the other fry survived off of the infusoria and aufwuch or whatever in such a small tank I'm not sure there would be enough to supply a dozen or so hatchlings. I like the VE because they should survive at least a week (possibly indefinitely if some reports are to be believed) in the tank so less chance of overfeeding and fouling the water. Only problem is the VE mostly seem to congregate at the surface so not sure how easily the fry will find them, hopefully there is just enough flow to keep them moving around in the rest of the water column.

 

Edited June 6, 2022 by KentFishFanUK
Spelling

[Guppysnail]

Sounds like your on the right track. Of the few I got to hatch I’ve not had fry survive to get markings. My VE cultures were a disaster.  My eyes are really bad.  I had a magnifying glass I was using to see if they had congregated at the top of the bottle, got to close and knocked the bottle off the counter onto tile flooring “smash” startled me and I jerked back knocking my second culture bottle to the same bottle smashing floor. 😝🤣. I have shrimp and baby mystery snails in my fry tank as well as CPD fry so They will consume the rest of the uneaten micro worms. My fry tanks are ugly tanks I encourage microfauna and algae in. I also have my bladder snail tank constantly packed full of microfauna in front of a west facing window that is always moderately green water to feed for infusoria.  

[nabokovfan87]

If you haven't seen it. Worth a watch.

 

Texture, color, location, size of the mop all can be relevant.

[Guppysnail]

So turned the lights on and found eggs in panda and Pygmy tank.  Here is prime laying spot. Almost dead anacharis floating about full of hair algae. 

I plucked leaves they were on. And put them in the coffee strainer floating box. 

[Chick-In-Of-TheSea]

On 6/6/2022 at 5:46 AM, Guppysnail said:

the pandas may be suspending the eggs. I find the eggs on single strands of hair algae floating in the middle of the tank as well.

My tetras are laying eggs on the roots of java fern that are freely swaying in the current.

On 6/6/2022 at 10:50 AM, Guppysnail said:

the coffee strainer floating box

I love this! How clever!

[Guppysnail]

On 6/6/2022 at 11:06 AM, Chick-In-Of-TheSea said:

freely swaying in the current.

30 seconds ago I just put in a handful of Salvinia minima to see if my panda and Pygmy would use the floating roots instead of me needing to pluck perfectly healthy leaves off. 

[Brian]

Sometimes it isn’t the surface, but the current.  I have had some aspidora catfish lay eggs on the water inlet of a HOB.  And a cory that would lay them on the inside of a sponge filter lift tube 

[nabokovfan87]

One of them was zooming around with eggs being chased by 5-6 fish.  I'll try to grab a photo in a little bit when she deposits the eggs somewhere.

Edit: didn't find any. I must've spooked her when I noticed it. I did another WC preemptively because I won't have equipment (until I get a new siphon) for a few days. I'll keep an eye out. I'm willing to bet the eggs will end up on the underside of the anubias.

Edited June 8, 2022 by nabokovfan87

[KentFishFanUK]

Ok so on Wednesday I collected a bunch of hair algae* and put it in the tank...

I tried to weight it down with some ceramic rings which seemed to work for a while but after a day or two half of it was spilling out, typical! Anyway checked it each morning and this morning (Saturday) I got home from my night shift to this...

And there are quite a lot of eggs in it, at least a dozen but I suspect closer to two dozen. So I pulled it all (not easy as it had become entangled with the java moss) and stuck them in an empty tank to see if I can raise them. 

So the hair algae definitely seems to work as a spawning media! But I need a way to keep it contained as for all I know they might have only used it because it was in the way of the java moss haha and if possible find a way to stop snails getting all over it (had to pull like a dozen ramshorn snails out of it as I'm pretty sure they munch on the eggs when they can). Any suggestions?

Edited June 11, 2022 by KentFishFanUK
Hair algae not hair grass

[Guppysnail]

@KentFishFanUK interesting thing last night in my Pygmy tank. They have been spawning for a few months but never on the glass. I had the canister flow turned down very low and the hob that releases water across the surface pushing against the front glass was unplugged feeding frozen brine shrimp yesterday. I forgot to turn the flow up and plug the hob back in so only flow was a ugf. I had eggs everywhere on the front glass for the first time. 
possibly the hair algae is protection from the flow? But flow itself inductee good lay time because in the wild it would mean higher O2 levels and less toxins?  Total guess but wanted to throw it out there. Hard to see them but I had about 15-20 scattered on the front glass. 

 

[Odd Duck]

That is very interesting.  I also find it interesting that they lay in much smaller clumps of eggs than my bronzes.  I’m looking forward to seeing how my other species of cories lay once they’re old enough.  See how it compares to my bronzes and other’s pygmies.

[KentFishFanUK]

On 6/11/2022 at 10:27 PM, Guppysnail said:

@KentFishFanUK interesting thing last night in my Pygmy tank. They have been spawning for a few months but never on the glass. I had the canister flow turned down very low and the hob that releases water across the surface pushing against the front glass was unplugged feeding frozen brine shrimp yesterday. I forgot to turn the flow up and plug the hob back in so only flow was a ugf. I had eggs everywhere on the front glass for the first time. 
possibly the hair algae is protection from the flow? But flow itself inductee good lay time because in the wild it would mean higher O2 levels and less toxins?  Total guess but wanted to throw it out there. Hard to see them but I had about 15-20 scattered on the front glass. 

 

Interesting! Definitely could be something to do with flow, didn't someone say after they hatch they are sensitive to flow? Maybe it's related. 

(Thought I have to ask, canister was low, hob was off.. ugf was on? How many filters do you have 😂) 

I have an internal power filter that provides quite a bit of flow pointed at/across the surface but the flow is much lower (going by the movement of particles and swaying of leaves) at the bottom of the tank. It's a bit of a jungle so I think all the plants slow it down quite a lot and it's a standard/high tank rather than a long - still yet to see an egg on the glass. Of course they could just be getting eaten before I see them