This Year Cory Eggs are not hatching!

[rcbows]

This year my Cory Eggs are not hatching. The very first batch I put in my net breeder system (See. http://ronsaquatics.com/2014/01/21/net-breeders/) did fine and are already removed from the growout tanks, but every spawn since then has not hatched. Last year I had excellent luck with my method. I didn't even have to use methylene blue in the tanks and no fungus. This year I am using methylene blue and I still get fungus. The fry that do hatch die about 2 days after hatch, and I can't find a cause. Spawning is not a problem. My Albino Aeneas sp. Cory's spawn practically everyday, with some eggs. I have spawned Bronze Cory's Aeneas sp. many times, Corydoras trilineatus once, Aspidoras albators, 3 times and Aspidoras spilotus once, but no luck hatching. I did get (2) Aspidoras spilotus from the very first spawn, but that's it. I have seen many babies in the hatch net but that's it, nothing to put in the growing tanks. All the BN eggs ,that the male BN's kick out of the nest and put in the hatch nets hatch and are not fungusing up! I just don't understand the problem I have enough air circulation coming up from the bottom of the tank, with a 6" air stone.

Any suggestion or comments would be most appreciated!

[rmc]

Have you tried using a "brand new" net breeder since the eggs started not hatching?
I use clear plastic containers to keep my cory eggs in both like this:
http://www.kensfish.com/aquarium-suppli ... edium.html

and like this:
http://www.kensfish.com/shipping-suppli ... -pour.html

I clean each container with hot water and paper towels between each use. I've found that if I don't give them a good cleaning the eggs are more likely to develop fungus and not hatch. If you try a new clean breeder net and the eggs hatch perhaps the eggs are being negatively affected by the old nets?

[Valb68]

I rinse out my plastic hatch tubs then set them out in the sun for a day or so. Rarely do I have fungus issues

[Karsten S.]

Hi,

this could be related to the tap water adders (polyphosphates). As far as I remember this can have similar effects.
Do you have brine shrimps, do these hatch (and survive) normally in your tap water ?

Cheers,

[rcbows]

To all that replyed to my post!

First:

Do you have brine shrimps, do these hatch (and survive) normally in your tap water ?

No I don't hatch brine shrimp yet I am working on it though!

Second:

This could be related to the tap water adders (polyphosphates). As far as I remember this can have similar effects.

What are (poly-phosphates) can you explain more?

Third:

Have you tried using a "brand new" net breeder since the eggs started not hatching?

I have used a new net breeder, for some batches of eggs, but I usually disinfect them with H2O2 (Hydrogen Peroxide) in between each new batch of eggs. it removes the brown tinge from the netting and makes it, look new again. It hasn't made a difference.

I did get a good hatch from two batches of Albino Aeneas the other day one batch survived but this morning I pulled out about a hundred dead white little larvae fry's from the 2nd net breeder batch. They weren't hatched in the morning and I couldn't check on them at night because I was at our club meeting. So when I came in, in the morning most had hatched and a lot have died. There are some that survived and I have been feeding them with "First Bites" from Hikari! It seemed to help!

Does anyone know if handling the eggs with your fingers is maybe the reason they fungus up? Also how long do you keep them in the containers you use and how long do you use Meth Blue. Do you use it on the fry for a few days or what.

[rmc]

I now handle almost every egg I collect with my fingers, and can't say that I've seen any more or less fungus than when I used to try to scrape them off with a razor blade. It took some practice, but I have much better results now collecting them with my fingers than I did when trying to scrape them off - I don't damage any eggs now - always did with the blade, but everyone is different.
In most cases I use a single alder cone in my 1 liter egg containers -these I just pop in there after collecting the eggs and adding an airstone and let it sit. Some sp. I've found the eggs don't do well with alder cones though and I have to use Methylene blue (Corydoras aeneus, C. paleatus, C. concolor, all the lasers, C.trilineatus, and Aspidoras spilotus - so far - I'm sure there will be more) If I add Methylene blue to the eggs in the container I add it right after I collect them and use an airstone in the the container. I then wait 24 hours and remove half of the water in the container and refill it with water from the tank the eggs were laid in. I do that every 24 hours from that point on until they hatch. When they hatch the water is hopefully relatively clear (not blue). I don't add anything to the water after they hatch. I wait 2 or 3 days and start adding a little microworms once or twice a day. I do a small water change on the container (20 to 30%) before adding the microworms each time again using water from the tank that the eggs were laid in. If there are a lot of fry I also try to add a small piece of java moss and/or a small piece of an old oak leaf that was in one of my tanks for a while to add some micro-organisms for supplemental feeding. 6 to 8 days after hatching I move the fry to a small tank usually 2 to 5 gallons with a sand substrate and a small sponge filter. I then start adding bbs once per day to the microworms and occasionally crushed pieces of sinking tablets/sticks. Once I start feeding bbs I can see the orange bellies in the fry so I know they are eating - if they've gotten this far I rarely have losses.

Cheers,

Rob

[Karsten S.]

Hi,

poly phosphates are increasingly added to the tap water by water suppliers (at least over here).
It is used to prevent corrosion and calcification just to name the main reasons for its usage.

Poly phosphates are difficult to eliminate from the water (unless you boil it) and the standard test sets are useless to detect them.
If you have problems with artemia nauplii (whereas they hatch when using rain water) this is a good indicator that you might have this problem. Perhaps you can also try to find out at your water supplier if they use poly phosphate.
Another sign could be increase algae growth (blue-green algae, diatoms, red algae/Rhodochorton).

Cheers,

[rmc]

A "phosphorous compound" is added to my city's water according to the local city water works' website. The reason it's added is to prevent scale and corrosion, and remove copper and lead from the tap water. Do you think this could be "polyphosphate"?

That being said Brine shrimp have no trouble hatching in my untreated tap water and I haven't had any trouble hatching Cory eggs, but I do mix my tap water with RO water (50/50) before adding it to any of my aquariums.

Cheers,

Rob

[rcbows]

There are no Poly phosphates in my water. Even if they were I use a double carbon bolk filter, de-mineralization and an R/O on my water which would eliminate it! Thanks

[rcbows]

Since I started using the cups and methylene blue in the water I have been having better results. After they hatch and or mostly hatch I put them in the net breeders(3) to a ten gallon tank and feed the Hikari First Bites and they seem to do fine now. I had one spawn of about 500 eggs from about 20 females and I put them all in one cup! That didn't work so the next batch of bronze/green Cory's I separated into two cups. There wasn't quite as many so we will see what happens. I set up a multi-stage air pump so I could run 8 cups of eggs with air stones at one time.

Ron Bows
http://www.ronsaquatics.com

[rmc]

Glad to hear you are having better results!

[dw1305]

Hi all,
I can't really help with the Corydoras fry, but I know a bit about phosphorus addition to potable water via my "day" job.

It isn't just polyphosphate (they also inject this into Chicken, Ham etc to make them hold more water), but also "orthophosphate" (PO4--- ion) that is added to tap water, usually with NaOH to ensure the pH remains above neutral. Polyphosphates chelate iron (Fe) and are often added to iron rich water, although they will complex a lot of other ions as well in water with less iron ions present.

Phosphate addition is usually to control "plumbosolvency" in the EU (EU Pb limits are less than 10 ppb, the technical terms for this is "PIMS - phosphate induced metal stabilisation" <http://dwi.defra.gov.uk/research/comple ... lvency.pdf>.

There isn't a maximum level of phosphorus for drinking water, as it is regarded as non-toxic, and I'd be surprised if it has anything to do with your fry death as you only need 1 - 5ppm in tap water for it to be effective.

Phosphorus doesn't have an aerial phase, so you can also be pretty confident that rain water won't have any phosphate present.

cheers Darrel

[rcbows]

I think the biggest problem with the Cory eggs not hatching is there infertility. There are so many eggs being laid in both of the C. aeneas species (Albino & Bronze) that they are not being fertilized properly. Also I can not put all of them in a small container and expect them to all hatch. I am separating them now into larger containers, but there are a lot of infertile eggs. White in appearance and they seem smaller than the others. There are so many its hard to pick them all out, they then start fungusing up and the fungus overwhelms the fertile eggs and they don'y hatch. I have got some good hatches and then some not so good, but most of the Cory's that were spawning spawned everyday or every other day, giving me about 200-300 eggs each time. Again I think most were not fertile. I have been using the methylene blue and the cup method with an air stone, but when the eggs start to hatch I move them to a breeder trap like I was using before. It seems to be working now! Thanks