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Using barometric graph to trigger corydoras breeding


infolific
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I've seen many posts and videos about using a colder-than-normal water change timed with a drop in barometric pressure to trigger corydoras to spawn. The commentary is typically vague about when to do the water change e.g. before a drop in pressure.

So I was wondering, if someone could provide more specifics. That is, using a graph like the attached and ignoring that some dates have already passed, when would you plan a water change?

Peak? Trough? In between? Does the total change from peak to trough matter? Is steepness of the drop a consideration?

bp.png

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If I'm trying to induce my corydoras to spawn, I typically try to do the colder water change the day of an incoming storm or the day before depending on how busy I am. I have not particularly seen a difference in the spawning behavior.

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Hi @infolific I recognize your name from another (older and much much smaller) forum. 🙂

Maybe others with more knowledge/experience will respond, but I don't think you need to chart/monitor the actual barometric pressure for success here. I think it's enough to keep an eye on the weather forecast, and watch for big weather shifts, like last night (for us).

Think of the nature equivalent... what does low pressure signal? Storm incoming. When does the water (in that natural system) get changed? During and right after the rainfall. My own thought is that the low pressure signals to the fish that good conditions (for fattening up, and laying eggs, and ultimately for egg survival and fry hatching/survival) are inbound. It's not that the low pressure is what's good, but rather it's signaling good times ahead, and be prepared to act now to take advantage of it. 

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On 6/14/2024 at 10:44 AM, TOtrees said:

Maybe others with more knowledge/experience will respond, but I don't think you need to chart/monitor the actual barometric pressure for success here. I think it's enough to keep an eye on the weather forecast, and watch for big weather shifts, like last night (for us).

This is actually what I did 🙂 No eggs. I'm trying to eliminate any misunderstandings I may have about when to do the water change. You're saying during or right after, but the previous reply in this thread says the day before or the same day.

On 6/14/2024 at 10:44 AM, T. Payne said:

If I'm trying to induce my corydoras to spawn, I typically try to do the colder water change the day of an incoming storm or the day before depending on how busy I am. I have not particularly seen a difference in the spawning behavior.

I tried the day of so I guess my next try will be the day before. Thanks.

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On 6/14/2024 at 11:37 AM, T. Payne said:

What species are you trying to spawn?

Just playing with sterbai at the moment which I believe are relatively easy to spawn, but I'm hoping to hone my skills before trying others.

I've bred other fish like red-lizard whiptails, angels, clown killifish, and pseudomugil furcatus, but deliberately introducing spawning triggers (aside from just good husbandry and feeding well) is new to me.

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I haven't found sterbai to be difficult in the least. In fact, I often don't induce spawning in my group, they breed readily without triggers. The main thing in my experience is feed extremely heavy, more than you think the fish would need. I feed pellets, frozen and live bbs and will often feed all 3 types of food in the same day.

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Ive only kept and bred sterbai and panda corys here but If I did the conversion right im running at 680 -750 mb at 9,200'. I tend to think the pressure trigger is always swittched on way up here and i just decode the others for the tougher species. Most adult fish spawn within weeks of arrival for me. 

I'd be curious on where in the pressure chart each cory species spawns and which species actually use a pressure drop and temperature increase to spawn. Im sure there are some habitats which actually would see a rise in temps with rain storms. 

This paper is a draft on corydoras

https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4684167

Some species here seem to have peer reviewed research on triggers

https://scholar.google.com/scholar?hl=en&as_sdt=0%2C6&q=corydoras+spawning&btnG=

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On 6/14/2024 at 11:49 AM, T. Payne said:

I haven't found sterbai to be difficult in the least. In fact, I often don't induce spawning in my group, they breed readily without triggers. The main thing in my experience is feed extremely heavy, more than you think the fish would need. I feed pellets, frozen and live bbs and will often feed all 3 types of food in the same day.

Yeah, I thought sterbai would be a good starter, but so far no luck for me. I'm pretty sure I have a mix of males and females based on their age and size. I've tried feeding what I considered to be heavy amounts and I found 1 sterbai dead the next day so that spooked me. I've tried freeze-dried blackworms, soldier-fly-based pellets, and xtreme cat scrapers. I don't have access to live worms, but BBS is an option although not one I would've thought of given their size. Maybe I'll try a more varied blend until the next low pressure cell.

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I've only kept Corydoras sterbai and Corydoras habrosus and they've both spawned for me. The sterbai I bought had all been surrenders to the LFS, so they were all adults when I got them (and yes, plied them with BBS, among other foods). The habrosus took a lot longer, because I bought them as juveniles. So depending on how old your sterbai are, you may just have to wait a bit for them to mature. I think @Lowells Fish Lab said his took until about seven or eight months old (see video below)?

The other thing I've anecdotally noticed is that flow seems to matter (something Lowell's Fish Lab seems to corroborate). After I clean my canister filter and the flow picks up speed, they seem more likely to spawn than before. Your mileage, as always, may vary.

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On 6/15/2024 at 11:26 AM, Rube_Goldfish said:

I think @Lowells Fish Lab said his took until about seven or eight months old (see video below)?

I follow Lowell's Fish Lab. Great videos. I've tried some of the things he mentioned including directed flow and a spawning mop. Nothing made a difference in my case. In the end it's probably going to turn out to be something silly and small that I've missed 🙂

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On 6/14/2024 at 11:46 AM, infolific said:

Just playing with sterbai at the moment which I believe are relatively easy to spawn,

I don't do much to spawn my Sterbai. But I can relate what I've observed.

They like to lay eggs in an area of flow. I keep a small powerhead in the back of the aquarium, pointing at the front, and where that flow hits the glass is where they attach eggs about 95% of the time. They still spawn without flow, but then where they place the eggs is completely random. So I use flow to make it easier to find and gather eggs.

Feeding them well helps.

Mine fish will sometimes coordinate a spawn with a water change, but maybe this is just coincidence. They have water changing on their tank every day iim moderate amounts (maybe a slow 20% change daily). I only do larger water changes if I see a bacterial bloom making the water cloudy, or after gravel vac'ing the sand. But the water I put in is the same temp as the water that comes out. Part of me wonders if they are reacting to the sudden appearance of cleaner water because the params other than 'cleanliness' don't change.

If they are coordinating their spawn with low pressure systems, I'm oblivious to that fact.

In general, I'm pretty hands off with these fish and they reliably lay between 20-40+ eggs a week, usually over the course of two consecutive days. 

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I can also relate my personal experience with Sterbai. My breeding group is currently 2 females and 5 males. I condition mine with freeze-dried tubifex worm, use a power head pointed at the glass or a spawning mop, and perform a cold water change. I don't time this with any barometric changes and I find success. That being said, I live in a convergence zone and we regularly have swings in pressure so YMMV. I do not find I need to do any further water changes after the initial cold water change in order for them to continue to spawn. However, I do notice that reducing flow significantly (like turning off the power head) will drastically reduce their spawning or have it cease altogether. After adding the ACO Easy Flow, I noticed that the power head isn't as much of a requirement for them anymore.

The biggest issue I face is them eating the eggs shortly after laying them.

Post-spawn is a whole 'nother thing.

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On 6/17/2024 at 7:03 PM, Maximus said:

The biggest issue I face is them eating the eggs shortly after laying them.

Oddly, mine don't touch their eggs. I routinely leave them there all day and collect them before I got to bed.

On 6/17/2024 at 7:03 PM, Maximus said:

Post-spawn is a whole 'nother thing.

Totally agree!

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On 6/17/2024 at 9:35 PM, tolstoy21 said:

Oddly, mine don't touch their eggs. I routinely leave them there all day and collect them before I got to bed.

Mine don't touch their eggs, either, but they're in my community display tank, and the bladder snails will eat the eggs, and lately the cardinal tetras have learned to wait for the eggs to be laid and then swoop in to try to pull them off the glass, with mixed success.

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Some of the species I've spawned, sterbai, bronze, and albino I haven't had to do much, just feed well with frozen bloodworms, live white worms and black worms. If it's another species, I will just watch the weather, and do a 50-75% water change with water that is 5° cooler anytime 12-24 hours before they say the storm system is supposed to come through. Doing that along with feeding heavily has worked good getting several species to spawn. 

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