My Cories Are Spawning Everywhere!

[The Lumpfish Guy]

Many creatures have large clutches because of predation, but I couldn't think of any that have large amounts because they struggle to develop.

Yes and no, There is also a bottle neck at the point of absorption of the yolk sac and the start of first feeding in ballan wrasse only 40% make it past this stage. This is common in many other species as well such as Atlantic halibut at 20%. (both aquaculture values) in the wild this would be even less.

It is a bit of a "difficult" life stage between these two points, as you are also still seeing development on the eyes, mouth, gut ect. If you are getting the yolk being absorbed before these changes can finish the fish will starve and die. This is obviously species specific,
I have found a paper in Korean which in the abstract (the only bit I can translate) says " Pre-larvae just after hatching were 4.35~4.68 ㎜ in overall length (mean 4.43±0.14 ㎜), their mouth and anus did not open, and they kept the yolk. Post-larvae on day 15 after hatching were 9.98~10.2 ㎜ long (mean 10.1±0.09 ㎜), the barbels around the mouth developed like saw teeth, and the dorsal, ventral, and anal fins, which had been membranous, were separated."

서비스 점검 - 교보문고

This suggests maybe what I said about mouth development is true?

I’ve just been doing searches but will get URL’s for further ones.

So I don't know if these links will help, or if you haven't come across already. They are quoting at least hatching success at about 70%, they say about 500 make it past 40 days per female, but don't give it as a percentage of egg produced.

https://search.proquest.com/docview/821515214?pq-origsite=gscholar&fromopenview=true

Breeding and Rearing of an Exotic Ornamental Catfish, Corydorus aeneus (Gill, 1858) in Kolkata, West Bengal and Its Economics - Proceedings of the Zoological Society

Cory cat, Corydorus aeneus (Gill, 1858) are popular among the hobbyists all over the world. They were reared successfully in glass aquaria and small cemented tanks in Kolkata, India. The females attained sexual maturity at the age of 12.2 ± 1.8 SD months while the males took 24.0 ± 1.6 SD months...

link.springer.com

 

[The Lumpfish Guy]

Ohh just spotted this Dr of Science thesis from Ghent,
Page 56 talks about juvenile morphology post hatch
But it seems to be quite a interesting read

Edit: URL didn't work so here is the title, should be able to search via google scholar " Early development of Corydoras aeneus (Siluriformes, Callichthyidae): a case study for understanding the evolutionary basis of loricarioid ontogenetic patterning "

 

[FishGuest5123]

Got some good reading to do. My cories lay 3-6 eggs in a clutch. The ones I lost were in the early stage of transitioning from yolk sac to fry food. They may have starved to death. Makes sense. I have 2 young females that may be too young to really breed healthy fry yet. The others are fine. I’ll read and watch. I have a bigger issue at the moment. My fry tank they are in seems to have lost the cycle. I have 0 ammonia, 50 nitrites (yikes) and 5 nitrates. I added some Prime and want to give a couple of hours before water change to allow nitrates to build a little more. Then I have to do a large change because fry could begin hatching tonight. @The Lumpfish Guy, @NCaquatics suggestions?

 

[The Lumpfish Guy]

So I may have missed this but what is your feeding regime like for the broodstock?
Broodstock age is not usually a large factor in truly Asynchronous spawning species and you might get better results with increasing the females food intake.

Did you manage to get the brine shrimp hatchery up and running? And when are you offering the first round of food?
Often earlier inclusion of live food will help as the movement of the prey is a large factor in first feeding success.

Where in the temperature range are you keeping the fry, hot, cold, mid range?
Can you afford to turn down the temperature 1 or 2 degrees? often the absorption of the yolk sac is related to temperature but the developmental processes eg mouth opening is not. So the first is using the "food" in the yolk sac for maintenance not development

 

[FishGuest5123]

So I may have missed this but what is your feeding regime like for the broodstock?
Broodstock age is not usually a large factor in truly Asynchronous spawning species and you might get better results with increasing the females food intake.

Did you manage to get the brine shrimp hatchery up and running? And when are you offering the first round of food?
Often earlier inclusion of live food will help as the movement of the prey is a large factor in first feeding success.

Where in the temperature range are you keeping the fry, hot, cold, mid range?
Can you afford to turn down the temperature 1 or 2 degrees? often the absorption of the yolk sac is related to temperature but the developmental processes eg mouth opening is not. So the first is using the "food" in the yolk sac for maintenance not development
[/QUOTEThe broomstick are fed Omega One Flakes (really for the tetras), Fluval dunking insect bites for bottom feeders, Omega One Shrimp pellets, and twice a week Veggie Rounds. I fed flakes and shrimp pellets in morning and bug bites in evening with a couple more Shrimp pellets. Very seldom, frozen blood worms.

I did get hatchery going. I started feeding New Life Spectrum Starter Growth on Day 3. After a couple of losses, I switched to my Hikari First Bites because although the NLS was not expired, it had been opened a couple of years ago. Day 6 I started feeding shrimp.

The temp is at 76F. Lower it?

 

[The Lumpfish Guy]

The broomstick are fed Omega One Flakes (really for the tetras), Fluval dunking insect bites for bottom feeders, Omega One Shrimp pellets, and twice a week Veggie Rounds. I fed flakes and shrimp pellets in morning and bug bites in evening with a couple more Shrimp pellets. Very seldom, frozen blood worms.

And each time you feed to Satiation?
you could maybe increase the food a little if not

The temp is at 76F. Lower it?

If you are at 76 I think you might be at the lower end, looking at a few of the papers they seem to keep them between 24-26 so 75-78? you might get away with reducing the temperature but I don't think that will make too much of a difference.

I did get hatchery going. I started feeding New Life Spectrum Starter Growth on Day 3. After a couple of losses, I switched to my Hikari First Bites because although the NLS was not expired, it had been opened a couple of years ago. Day 6 I started feeding shrimp.

So often in first feeding in Commercial hatcheries brine shrimp are offered quite early. The movement of the live prey and induce feeding behaviour in many fish species. I don't know if this is the case in Cories but it might help

The main point is you don't want to be offering food after the Yolk sac has been used up at this point the fish is going to be too far gone. You want to be offering food before this happens.

So a paper "recent developments in the application of live feeds in freshwater ornamental fish culture"
https://doi.org/10.1016/S0044-8486(03)00512-X

This is suggesting that Corys require "small zooplankton such as rotifers for fry production" The paper seems to be suggesting that maybe marine rotifers might be the way to go due to the smaller size. But I think any live food offered early is definitely going to help

 

[The Lumpfish Guy]

I will preface by the way and say I have not (yet) bred Cory's and am drawing on experience with other species. So If I am saying stuff which doesn't apply to the species someone just shout up ( looking at you @NCaquatics )

 

[AdoraBelle Dearheart]

Ohh just spotted this Dr of Science thesis from Ghent,
Page 56 talks about juvenile morphology post hatch
But it seems to be quite a interesting read

Edit: URL didn't work so here is the title, should be able to search via google scholar " Early development of Corydoras aeneus (Siluriformes, Callichthyidae): a case study for understanding the evolutionary basis of loricarioid ontogenetic patterning "

Dang, this link doesn't work!

But what you're saying makes complete sense, and the info about mortality rates and breeding in the other species is still helpful! It makes sense that if the mouth and anus haven't opened yet, yet the yolk has been absorbed already, the fry wouldn't make it. Next time, I'd try to feed a little earlier, has to be worth a try, and it's less risky with live foods than with something like egg yolk.

I appreciate the research and the suggestions! You might not have bred cories, but you have super relevant experience with commerical fishery practices, and some of that is bound to translate.

 

[AdoraBelle Dearheart]

I will preface by the way and say I have not (yet) bred Cory's and am drawing on experience with other species. So If I am saying stuff which doesn't apply to the species someone just shout up ( looking at you @NCaquatics )

You should breed some corydoras, they're adorable Mine are two weeks old today

 

[The Lumpfish Guy]

Dang, this link doesn't work!

But what you're saying makes complete sense, and the info about mortality rates and breeding in the other species is still helpful! It makes sense that if the mouth and anus haven't opened yet, yet the yolk has been absorbed already, the fry wouldn't make it. Next time, I'd try to feed a little earlier, has to be worth a try, and it's less risky with live foods than with something like egg yolk.

I appreciate the research and the suggestions! You might not have bred Cories, but you have super relevant experience with commercial fishery practices, and some of that is bound to translate.

I have updated with the thesis title, if you copy that into Google scholar it should come out for you it's free to access too.

It is possible that they don't require life food to start feeding, it really just depends on their life history. take the lumpfish for example it will just go directly to pellets (dust size). But even so there are many studies which continually demonstrate the usefulness of feeing live prey as a first food, including gut development, calcification of bones, and establishment of behavioural cues for feeding. the only down side is that Artemia (Brine shrimp) are poor in many of the require EFA's and often require enrichment in Aquaculture.

I appreciate the research and the suggestions! You might not have bred cories, but you have super relevant experience with commerical fishery practices, and some of that is bound to translate.

not to brag... It helps that my PhD is in broodstock management and egg quality as well

 

[The Lumpfish Guy]

You should breed some corydoras, they're adorable Mine are two weeks old today

I have had egg from them, but never got round to doing them.
I have done quite a few other species like Angels, Discus, but when you do it for work its not the first thing you want to do at home

 

[AdoraBelle Dearheart]

I have had egg from them, but never got round to doing them.
I have done quite a few other species like Angels, Discus, but when you do it for work its not the first thing you want to do at home

But... but... cute! You can see his little tail!

 

[AdoraBelle Dearheart]

I have updated with the thesis title, if you copy that into Google scholar it should come out for you it's free to access too.

the only down side is that Artemia (Brine shrimp) are poor in many of the require EFA's and often require enrichment in Aquaculture.

Reading that thesis now


I've been feeding First Bites and a lot of Microworms, how do microworms stack up?

Starting adding some frozen cyclops, rotifers, daphinia and moina too now that they're a little larger (not all at the same time of course)

 

[FishGuest5123]

@The Lumpfish Guy my first tank that has my first set of fry in it was set at 76.5. So perhaps this new batch at 75F will help. I will begin feeding day after birth just in case. I can syphon out if they don’t eat. I got my tank back in line on parameters. Had a heart attack earlier. I had to wait to feed the brine shrimp last time because I thought I had some eggs and didn’t so had to wait 2 days for delivery. I really appreciate this info. I feel so bad if their mouth doesn’t develop. How awful! Have eggs hatching in the brine shrimp hatchery to feed for dinner. I normally feed shrimp once a day and First Bites twice a day.

 

[The Lumpfish Guy]

Maybe, the lower temp might help them it will certainly slow down the use of the yolk sac.

It's hard, it's not great when they don't develop but at the same time there is very little you can do at that stage. All of the development up to the point of first feeding is controlled by the environment (temp usually) and the nutrients contained within the eggs. so they best thing to do is try and influence it on the broodstock end and accept that even with 30 years of international investigation (and Literally Billions of £'s) behind doing this in aquaculture the best results for this stage for some species can still be as low at 20-30% survival. Edit: And that is after maybe 30% loss at hatch. so you are looking at the end result after weaning (going from live to pellets) at less than 10% of fertilised eggs surviving.

I've been feeding First Bites and a lot of Microworms, how do microworms stack up?

I don't know, I have never used them. The main ones for Aquaculture are Brine shrimp, Copepods and Rotifers. I would guess that if they are quite small they probably will be ok