Anyone know of a journal for hatching Aeneus at different temps?

[Ltygress]

"Three to five days depending on species and temperature."

That's what EVERYTHING says.

But what about something more definite? Has anyone kept a journal, tried experiments, or otherwise "tested" the hatch rates of different cory eggs?

The only cories I have right now are Aeneus - black "venezuelan" and orange laser. Of course they're the easiest to spawn, so they'll be easiest to experiment with. My biggest challenge is ambient room temperature. Some of the rooms in my house fluctuate horribly! And those are pretty much the rooms with the only places to put the tanks (the only ones with enough wall outlets).

But if such a journal or experiment has already been done, then I certainly don't need to make another one.

[bekateen]

Hi Ltygress,

What's your rush? The difference between 3 days and 5 days is only two days. Given how long it takes hatchlings to grow to sellable size, those two days are inconsequential for most people. On top of that, individual fry within a clutch will show immense variation in growth rate, so some may grow to be a certain size in 3 months, and other individuals need 6-8 months to reach the same size. I guess I'm thinking that in the bigger scheme of things, 3-5 days is probably a "close enough" estimate of hatching time. But to address you questions, read on:

Physiologically, it's generally true that chemical reactions and animal physiology/growth occur faster at higher temp, so implicitly the warmer the faster (for now we'll ignore the fact that excessively high temperatures then damage organic molecules and slow physiological processes).

But there are also slight variations between individuals due to genetics and other circumstances we can't control or don't see. I've had lots of

Corydoras aeneus

spawns, and 3 days is the typical time to hatch. But I've had other aeneus clutches take 4 days, and most recently I had one clutch that appeared to hatch in just over 2 days (maybe 50-60 hours)... and that fast clutch hatched at room temperature (mid 70's), not even heated!

Also, keep in mind that a single female may take hours to lay all of her eggs too, and some females hold part of their clutch and lay the eggs over a 1-3 day period (e.g, my diphyes do this). Complicating matters is that within a spawn, not all eggs hatch at once. So in a "3-days-till-hatching" spawn, the first eggs may have hatched after 2 days, and there still may be some eggs that won't hatch until day 4.

And all of that is just within one species. Muddling the water even further is the reality that what we call "aeneus" is probably more than one species, a lot more. And each species in this group might have a slightly different incubation time.

The best piece of advice I can offer you is to not get fixated by what other people tell you is supposed to happen, but rather, just learn how your fish behave and adapt your routines to your fish.

But to answer your specific question, yes lots of people have kept detailed logs on hatch times. If you click on individual BLOG reports here, or if you are a member of CorydorasWorld.com, you will find plenty of reports listing incubation temps and incubation times. Also, many of those reports include temperature data, so that will help you sort things out.

Good luck,
Eric

[Ltygress]

Oh it wasn't about rushing mine. I am just curious as to EXACTLY how temperature affects hatching times, and documenting it. And after that, yes, documenting the hatch rates at the various temperatures too. I'll check out the corydorasworld.com though. Maybe I'll find both of my answers in one!

[bekateen]

Okay. I'm going to go out on a limb here and suggest you probably won't find the answer you're looking for, at least to a satisfying level. I'm saying this for three reasons: (1) People report time to hatch in days, not hours. That means each entry can be off +/- by half a day, which is a lot of wiggle room if you want to see a subtle effect (I.e., temp effects will be visible in hours of development, not always days). (2) Since eggs are often laid overnight, there's potentially a lot of slop in how the days get recorded, given point (1) above. And (3) For all the reasons I listed above, even a well documented, hour-by-hour analysis for a species like "aeneus" is going to be highly variable.

Unless you want to run a carefully controlled experiment with 24-hr monitoring, adjusting for exact time of laying of individual eggs, and applying statistical assessment to the results, you aren't going to find an answer that is both more precise (than the general answer above) and universally applicable to other species.

Cheers, Eric

[bekateen]

FYI, here is the data available from PlanetCatfish for

Corydoras aeneus

, based on all the BLOGs that report both temperature and time to hatching (a total of 8 different BLOGs, plus a second entry (described above and below) from my own experiences). For any reports that list a range of temperatures, I plotted them as the average temp. From the non-averaged data, the minimum temperature reported was 20C and the maximum temperature reported was 26C.

I've added an additional data point of my own which I referenced above - a recent laying by a single female, after which hatching took place two days later (eggs discovered on a Sunday morning ~9AM (laid overnight Saturday) and nearly all eggs had hatched when I awoke Tuesday morning ~8AM (hatched overnight Monday)): That's just 48 hours from discovery of eggs till discovery of fry, and I can attest that neither were present at 10pm the night before on either of those days (Saturday/Monday)... At its most extremes (unrealistically assuming laying and hatching were instantaneous events, each occurring the moments after or prior to my inspections), this cannot be less than 37 hours (9AM Sun to 10PM Mon) or exceed 58 hours (10PM Sat to 8AM Tues). This information is not in the formal categories of temperature and hatch time, since there is no ability to report multiple spawns independently, but I've added the info to the text of my BLOG.

I've also added a trendline through the data, but as you can see there is one report which is outlying from the trend, so I excluded that from the trendline analysis.

Again, keep in mind that all these reports treat "hatching time" as a singular event for all eggs in each clutch, but in so doing, the data ignore the fact that some eggs hatch earlier and others later than the reported times. Moreover, there is no standard followed in these BLOGs as to whether the "hatching times" reported are times for the first egg to hatch in each clutch, for most of the eggs to hatch, or for the last eggs to hatch. The time range from first egg to hatch until the last egg to hatch may exceed 24 hours.

I hope this helps.

Cheers, Eric

P.S., With the exception of the one report at 26C/5 days, I'm surprised at how remarkably "clean" the other nine BLOG data points are in terms of showing a relatively good temperature effect.

[Ltygress]

Understandable. I think in order for any reliable information to come from it, all of the "testing" first needs to be done by the same person. Second, it needs to be in a controlled environment. Those two rooms I have with variable afternoon temperatures may not be good enough. Quite frankly, I may need to find a closet if I do this at all! LOL!

Keep in mind that most of this reply is random thoughts in my mind about it, and me just typing it out as I think about the various issues and solutions. So I'm "thinking out loud" here.

Third, it needs to be the same type. At the moment, I only have blacks (venezuela black, but thought to be Aeneus) and orange laser (supposedly Aeneus variant). I'm trying to get red laser and green laser from an inexpensive source, but that will take some time for each of my sources to actually get them, too. The orange laser I have are still too young to breed. The blacks are laying like crazy. While cories are great in planted tanks (not counting the SHALLOW-rooted plants they dig up), I'm probably about to kill every last plant I have just cutting leaves off to save cory eggs because there are so many.

Although I do have one advantage - I have surveillance cameras. I have four of them set up around the perimeter of my house (no, I'm not in a good area, but that's a whole 'nother story that doesn't belong here), but the system can take four MORE cameras as well. I just don't have the actual cameras for those, because I didn't think I would need them, so I only ordered it with four cameras. And the cameras have night vision as well. Fish tanks light up just like they were in daylight, although the picture is in black and white.

But I can order the extras and connect those to point directly at the cory tank to see exactly WHEN egg-laying begins. It would probably also be important to know how long egg-laying continues and ends, since mine took roughly 6 hours last time to lay all of the eggs. Then I could average that time out and use that as the "time laid".

Another camera or two could go onto the hatch tank. Then I could see when the first one hatches, and when the last one hatches, and average that time out, as well.

Again, this is all just thinking out loud. I have the resources to do it, I simply have to iron out details in my mind.

[Ltygress]

Also, I have a feeling the one anomaly on your chart had to do with oxygen deprivation of the eggs. We know warmer water holds less oxygen than cooler water. And cories really don't like warmer water in general, especially as a bottom dweller. So maybe the warmer water slowed down the hatch because the eggs weren't getting the oxygen they needed for proper development.

[bekateen]

Yes, I didn't inspect the info on aeration, etc. Neither did I check hatch rate, so whether higher or lower temps had a negative effect on the percentage of eggs hatching is not assessed.

It sounds like you have a mission. . Good luck and let us know what you experience and learn.

Cheers, Eric