Corydoras Sterbai eggs not hatching because of hard water?

[Flavoi1]

 

I have a group of 8 Sterbai Corys that recently started to lay eggs in my 45g comunity tank.

I pulled some eggs a few times and put them in a hang-on breeding box for hatching.

The eggs develop just fine and on the day I expect them to hatch they start wriggling but never break out of the shells. After a couple of days they stop moving and die.

My guess is that my local tap water is just too hard and somehow make the eggshells to tough for the fry to berak.

My tapwater has a kh of around 11-12 and gh of 30+ and ph of 7.6-7.8 the last time I checked. Since my Fish seem happy, my chery shrimp breed hundreds of babies and all the plants grow like weeds I never bothered adjusting the water except of adding some dechlorinator.

 

What are your thoughts on this?

 

Edit 1: TLDR of the answers as of May 30th:
It's possible that the high GH is somehow preventing the fry from hatching, but we're not sure.
A possible solution/way to test this would be to use either RO water or a chemical additive to lower the GH and see if the fry hatch. Since I'm not actively trying to breed the Sterbais, I'm not gonna mess with my tank at this time, but if I change my mind, I'll update this post with my findings.

Edit 2: Sooo... It's still the 30th of May, just a few hours after edit 1. I have a new spawn of 25 eggs. Will update regularly on how the hatching goes.
 

Edit 3: Posted some pictures an videos of the eggs, I took with my phone and a microscope. 

Edited June 2 by Flavoi1

[Unemployed Fish Nerd]

I don't have a lot of experience with corys (none at all, in fact 😅😅😅) but this has happened to my Zebra Danios. 

[Tony s]

On 5/27/2024 at 5:38 AM, Flavoi1 said:

gh of 30+

That can be an issue. Usually more sensitive species. But, man that’s a high gh. Not worried about the ph, kh. If you have a water softener in the house, it will strip the gh from your water. Then you could mix it with your normal aquarium water source and get something around a 10 gh. Still hard, but much less so. 

Getting a 10gh shouldn’t bother either your plants or shrimp. I might do it slowly so to not your shrimp.

[mountaintoppufferkeeper]

Do you have photos of the process with your eggs? That would be interesting to see.

My coop test strips do PPM. Im not sure what 10 GH converts to in PPM but : my parameters here are 300+ ppm GH //30-40 ppm KH // PH 6.8-7.0 

Not all the total dissolved solids that make up everyones GH are the same im sure. It is possible that there could be something dissolved in your water that hardens the eggs. 

I do run lots of live plants its possible they are eating something that would otherwise harden egg shells. Ive hatched panda cories, sterbai corys, multiple puffer species, and some dwarf pikes here without a shell issue. 

[Tony s]

On 5/27/2024 at 11:17 AM, mountaintoppufferkeeper said:

Im not sure what 10 GH converts to in PPM

18 ppm per dgh or dkh. Close enough I just use 20

So 30 dgh is roughly 600ppm. And your 30-40 ppm kh is between 1-2 dkh. Low but doable. 

[mountaintoppufferkeeper]

ThankS @Tony s.   I may pull out the tds meter and check to see the true reading. i know im above 300 ppm not a clue by how much.

That KH only gets to that level using crushed coral, and clam shells to buffer. Mountain water ....lots of tds and minimal kh out of the tap. 

[jwcarlson]

If those hardness numbers are accurate, that could be an issue.  My sterbai hatch successfully in my tap water 20-22 dGH and similar for dKH.  I haven't tested it for awhile.  

To test your theory, get a gallon of distilled water from Walmart and put your eggs in that.  Do you use any methylene blue?  Eggs don't hatch well for me without MB.

[mountaintoppufferkeeper]

Looks like mine is 454 on the TDS meter .... a little above 300

[Flavoi1]

On 5/27/2024 at 2:43 PM, Tony s said:

That can be an issue. Usually more sensitive species. But, man that’s a high gh. Not worried about the ph, kh. If you have a water softener in the house, it will strip the gh from your water. Then you could mix it with your normal aquarium water source and get something around a 10 gh. Still hard, but much less so. 

Getting a 10gh shouldn’t bother either your plants or shrimp. I might do it slowly so to not your shrimp.

@Tony s I try to minimize the additives I add to the tank but I'm looking into getting a RO-unit to slowly dilute my tapwater with RO water and keep consistent water after I get to a point I like and the fish are happy.
 

On 5/27/2024 at 6:17 PM, mountaintoppufferkeeper said:

Do you have photos of the process with your eggs? That would be interesting to see.

My coop test strips do PPM. Im not sure what 10 GH converts to in PPM but : my parameters here are 300+ ppm GH //30-40 ppm KH // PH 6.8-7.0 

Not all the total dissolved solids that make up everyones GH are the same im sure. It is possible that there could be something dissolved in your water that hardens the eggs. 

I do run lots of live plants its possible they are eating something that would otherwise harden egg shells. Ive hatched panda cories, sterbai corys, multiple puffer species, and some dwarf pikes here without a shell issue. 

 

@mountaintoppufferkeeper No, I did not take pictures but will do if I get to it in the future. My GH is about 580 ppm and 200 ppm CaCO3 (KH) depending on the season, we have very hard water around here...

Hmm... I have lots of live plants too, maybe my corys just need some more time since they just startet laying eggs a few weeks ago.
 

On 5/27/2024 at 8:39 PM, jwcarlson said:

If those hardness numbers are accurate, that could be an issue.  My sterbai hatch successfully in my tap water 20-22 dGH and similar for dKH.  I haven't tested it for awhile.  

To test your theory, get a gallon of distilled water from Walmart and put your eggs in that.  Do you use any methylene blue?  Eggs don't hatch well for me without MB.

@jwcarlson I guess those levels could be harmfull to some fishes but since even my ottos are happy I guess it's something else.
I had the same idea about trying to hatch them in destilled water. Will do that the next time I get around to collect a few of the eggs.
I didn't add MB but I also never had problems with moldy eggs. In fact until now every single egg I saw was fertilized, like 100% of the egs. That inof itselfe is crazy to me 🙂  

Edited May 28 by Flavoi1

[tolstoy21]

On 5/27/2024 at 12:17 PM, mountaintoppufferkeeper said:

My coop test strips do PPM. Im not sure what 10 GH converts to in PPM but : my parameters here are 300+ ppm GH //30-40 ppm KH // PH 6.8-7.0 

dGH x 17.9 = ppm

[Tony s]

On 5/29/2024 at 7:05 AM, tolstoy21 said:

dGH x 17.9 = ppm

Very correct. But sooo much easier just to use 20. Gives you a rough idea and close enough for biological systems 

[Tony s]

On 5/27/2024 at 6:38 AM, Flavoi1 said:

gh of 30+

So no household water softener? The only thing you’d be adding by using it would be a trace amount of salt. Which really wouldn’t do anything. Ro would also work to mix your water. But costs $. And can be slow, depending on the system you buy and how much you need. You’ll also need a holding vessel. I use a 30g brute trash can with wheel attachment. And a pump to move water.

you could use the softener for now and use the Ro when you get it.

[tolstoy21]

On 5/29/2024 at 7:45 AM, Tony s said:

Very correct. But sooo much easier just to use 20. Gives you a rough idea and close enough for biological systems 

Sorry, didn't see that you had already posted that until after I had replied.

 

On 5/29/2024 at 7:58 AM, Tony s said:

So no household water softener? The only thing you’d be adding by using it would be a trace amount of salt. Which really wouldn’t do anything.

The only thing one would need to be careful of with a softener is that with 0 dGh, any plants in the aquarium will do poorly. Agreed that the trace amounts of sodium introduced into the water are negligible. I run a nitrate filter that recharges with solar salt, just like a water softener, and have never seen any ill-effects on fish or plants after many years.

On 5/29/2024 at 7:58 AM, Tony s said:

Ro would also work to mix your water. But costs $. And can be slow, depending on the system you buy and how much you need. You’ll also need a holding vessel. I use a 30g brute trash can with wheel attachment. And a pump to move water.

 I do the same exact same thing! I'll use RO to bring down my GH for some species of fish when I want to trigger them to breed (I have 9Gh in my water), and for caridina shrimp.  

[Flavoi1]

On 5/29/2024 at 1:58 PM, Tony s said:

So no household water softener? The only thing you’d be adding by using it would be a trace amount of salt. Which really wouldn’t do anything. Ro would also work to mix your water. But costs $. And can be slow, depending on the system you buy and how much you need. You’ll also need a holding vessel. I use a 30g brute trash can with wheel attachment. And a pump to move water.

you could use the softener for now and use the Ro when you get it.

I have a water softener for washing clothes on which is written: Made from citrate salt, based on natural citric acid. Free from perfume, colorants, microplastics and animal ingredients.

Do you mean a water softener like this or are we talking about somehing else and I don't get it because of the language barrier?

[tolstoy21]

@Flavoi1  My sterbai spawn and hatch almost every week. My water is 9dGh and 0dKh. Ph runs around 6.4-6.6. I wonder if Kh could be a contributing factor for you, not necessarily GH.  Just a thought (or guess).

On 5/29/2024 at 8:22 AM, Flavoi1 said:

I have a water softener for washing clothes on which is written: Made from citrate salt, based on natural citric acid. Free from perfume, colorants, microplastics and animal ingredients.

Your water softener is an external unit that has a large drum next to it full of salt?

Edited May 29 by tolstoy21

[Flavoi1]

On 5/29/2024 at 2:23 PM, tolstoy21 said:

@Flavoi1  My sterbai spawn and hatch almost every week. My water is 9dGh and 0dKh. Ph runs around 6.4-6.6. I wonder if Kh could be a contributing factor for you, not necessarily GH.  Just a thought (or guess).

Good point, just yesterday I was looking at a KH/PH down and wondered if that would help. The thing is, I added my old co2 system a couple of days ago and now my PH is slowly going down. I'm afraid that if I add the KH/PH down my PH will be way to low... 

[Flavoi1]

On 5/29/2024 at 2:23 PM, tolstoy21 said:

Your water softener is an external unit that has a large drum next to it full of salt?

No sorry... its an additive for washing clothes you add manually like a detergent.

[Tony s]

On 5/29/2024 at 8:28 AM, Flavoi1 said:

I'm afraid that if I add the KH/PH down my PH will be way to low... 

Honestly, I usually don’t worry about ph/kh. As long as it’s consistent fish adapt just fine. Carbonates in water are not going to do a lot but buffer and stabilize your ph. The high amount of calcium/magnesium could cause issues. If you can get it to 10 dgh you should be fine. 

If your co2 system is new, run that for a few weeks or a month. Learn it first. Figure out what it does to your water. We often try to change too much at once and miss learning things we should. Most times patience works in our favor.

[tolstoy21]

On 5/29/2024 at 8:28 AM, Flavoi1 said:

I'm afraid that if I add the KH/PH down my PH will be way to low... 

I tend to stay from these products. Admittedly, I will use muriatic acid to tank the Ph to breed certain fish, but you need to be careful with that and test quite a bit to get it right.

In general, if you want to dial in certain params, go with RO and either cut your water with it or remineralize it to where you want your params to sit.

I hatch all my sterbai in a 2 gallon aquarium. It would probably be very cost effective for you to use something like that and just mix it like 70/30  RO/tap water. You could also use rain water or distilled water. If you don't have an RO unit, you should be able to buy RO water from a aquarium store that also sells reefing stuff.

Just add an airstone to keep the water moving and maybe something with anti-fungal properties to help the eggs not fungus over.

 

Edited May 29 by tolstoy21

[Tony s]

On 5/29/2024 at 8:35 AM, Flavoi1 said:

its an additive for washing clothes you add manually like a detergent.

I must admit, that’s a new one for me. Never heard of doing it that way. Our normal tap is about 15dgh and we treat every bit of water we use.it’s connected to the water supply before using it. Doing it this way helps to increase the lifespan of most appliances. Things like water heaters, dishwasher, ice makers. The aerators on all faucets stay cleaner as well. It also has a noticeable effect on your skin and hair from the shower. But each place is different. Nothing wrong with what you’re doing, just a different method.😃

Spoiler

 

 

[Flavoi1]

On 5/29/2024 at 2:46 PM, tolstoy21 said:

I tend to stay from these products. Admittedly, I will use muriatic acid to tank the Ph to breed certain fish, but you need to be careful with that and test quite a bit to get it right.

In general, if you want to dial in certain params, go with RO and either cut your water with it or remineralize it to where you want your params to sit.

I hatch all my sterbai in a 2 gallon aquarium. It would probably be very cost effective for you to use something like that and just mix it like 70/30  RO/tap water. You could also use rain water or distilled water. If you don't have an RO unit, you should be able to buy RO water from a aquarium store that also sells reefing stuff.

Just add an airstone to keep the water moving and maybe something with anti-fungal properties to help the eggs not fungus over.

 

I think I'll have more peace of mind with the RO unit but for now I won't mess with the tank🙂

Since I'm not actively trying to breed the Sterbais I have no need for a separate breeding tank but I'll keep your recommendation in mind for when the time comes. Sounds much easier than messing with my main aquarium.

On 5/29/2024 at 2:49 PM, Tony s said:

I must admit, that’s a new one for me. Never heard of doing it that way. Our normal tap is about 15dgh and we treat every bit of water we use.it’s connected to the water supply before using it. Doing it this way helps to increase the lifespan of most appliances. Things like water heaters, dishwasher, ice makers. The aerators on all faucets stay cleaner as well. It also has a noticeable effect on your skin and hair from the shower. But each place is different. Nothing wrong with what you’re doing, just a different method.😃

  Reveal hidden contents

 

 

Well those are two different things. Newly constructed homes/buildings do have a setup like you described but I live in an older Building where the new regullations/building standarts weren't in place at the time of construction. 

[Tony s]

On 5/29/2024 at 9:12 AM, Flavoi1 said:

Building where the new regullations/building standarts weren't in place at the time of construction.

Understand. And if you rent/ lease, the property owner isn’t going to pay for the upgrades. 

[mountaintoppufferkeeper]

Thanks much @tolstoy21 ill keep that handy moving forward

[Guppysnail]

@Flavoi1 I’m jumping into this conversation late but wanted to share 2 things I’ve learned hatching many types of corydora eggs.  My tap water is like liquid rock with crazy high gh/kh. Before you go to extreme measures altering water just to hatch these buy a gallon jug of Walmart purified drinking water. That is RO.  Distilled water works fine also I’ve used that before. Use that mixed with your tap to hatch.

On 5/27/2024 at 6:38 AM, Flavoi1 said:

the day I expect them to hatch they start wriggling but never break out of the shells. After a couple of days they stop moving and die.

This statement stands out to me. If they are moving wiggling at all the have most likely hatched.  The fry still look like an egg but if you use a magnifying glass you can see a tail. The translucent tail emerges yet they still look like an egg. 
They wiggle for a few days before they eat.

My hastatus just hatched this morning and are a great example since they remain like this for an entire day before moving. You need to blow the photo up really large they are tiny. This photo is phone on max zoom looking through a magnifying lens as well to see the tail  

I cannot use hang on outside breeder boxes. My home is to cool and both fishrooms are just converted spare bedrooms.  My hang ons even the flow through ones get to cool. I learned this with corydora eggs.  Mine would get to the stage of the photos I posted and stay there wiggling for a few days then die exactly as you described.  
To combat this I for go the flow through part and turn them so they hang inside the tank. I drop in an airstone to compensate. The downside is lots of water changes though. 
 

Just some thoughts to try and help. Corydora are my all time favorite species to breed. Best of luck. 

[Flavoi1]

@Guppysnail Hey, thanks for sharing this with me, I too put the box into the aquarium to equalize the temps.
 

On 5/30/2024 at 12:28 PM, Guppysnail said:

This statement stands out to me. If they are moving wiggling at all the have most likely hatched.

I'll look into this with the next spawn but I'm pretty sure that my fry aren't hatching cause I never found empty eggshells and there is nothing in the box that would eat it like snails or shrimp. 
Do you have any tips for when the fry indeed are hatched like you suggested? What could be the cause and what could I do to remedy it?