Breeding Cory's with Shrimp in Tank

LHanna61

HI Everyone--
I was wondering if there was a different way to promote breeding within Cory's WITHOUT the temp changes typically used.

For those that aren't familiar, shrimp are VERY sensitive to temperature changes. So when adding water back into the tank, they have to match within one degree or they get shocked and die within days. I've done this a couple times by accident, especially in my beginning days of shrimp keeping.

I recently drained my tank down to catch some fish to sell and when I added the water back in (about 20 gallons worth in a 30 gallon tank) I shocked my shrimp and killed off about 5 of them (out of 30-40)-- not the end of the world but also quite tragic at the same time. This, however, resulted in a spawn from my Corydoras. Luckily I was fast enough and collected 33 eggs. Since I wasn't expecting to breed them, I didn't have any way to prevent the eggs from molding so I lost a large majority of them with only 9 surviving. At this time, I took the heater out of the tank so that I could have a more naturally balanced tank for the shrimp (also summer is around the corner.) A couple days later, I noticed some more eggs in some moss (freshly hatched and fertilized) and collected about 10-- I must have been too late to get the rest that might have been on the glass.

1) I was wondering if the Cory's going from having a heated tank to a tank that fluctuates naturally throughout the day +/- 1 degree prompted the most recent spawn? Is this something you think I could do regularly? (use a heater for a month or two and then take it out for a week? and see what happens?)
2) I don't want to catch them out of the 30 gallon but if I DID-- I have a small breeder box on the tank-- could I put two males and one female in there over night and pour some cooler water in that or is that too small of a space (roughly 7"x5")?
3) I also have a 20 gallon that's currently empty that I could occasionally move them to but will that stress them out? Could I get away will not cycling that tank and just letting them hang in the tank for a day or two?

Just curious-- not trying to create an army of cory's or anything.

Thanks for the insight!
 

Demeter

I do water changes in my cherry shrimp tanks without bothering too match the temp exactly, if I'm off a few degrees it doesn't bother my shrimp at all but perhaps yours are a more fragile species/strain. You may want to look into testing your tap and then your tank water, sometimes the pH varies enough between new and old water that is will shock the fish, one reason why many people choose to age their new water by letting it sit out for a couple days before doing a water change. Just something to think about.

As for the corries, temperature changes are key but often times when the atmospheric pressure changes (like when a storm is rolling in) it will cause them to spawn. If you were to move the group to the 20gal for spawning I'd imagine you'd only need one good spawning session to get plenty of eggs. I think that is a good option.
 

LHanna61

I do water changes in my cherry shrimp tanks without bothering too match the temp exactly, if I'm off a few degrees it doesn't bother my shrimp at all but perhaps yours are a more fragile species/strain. You may want to look into testing your tap and then your tank water, sometimes the pH varies enough between new and old water that is will shock the fish, one reason why many people choose to age their new water by letting it sit out for a couple days before doing a water change. Just something to think about.

As for the corries, temperature changes are key but often times when the atmospheric pressure changes (like when a storm is rolling in) it will cause them to spawn. If you were to move the group to the 20 gallon for spawning I'd imagine you'd only need one good spawning session to get plenty of eggs. I think that is a good option.
that makes sense about the water changes-- I usually use tap water (for this tank) but I've been doing 50/50 RO water recently so that makes sense
 

DoubleDutch

There are three other possibilities that might trigger :

1 waterchanges with water with different parameters (even adding ferts sometimes does that)

2 let the water splash into the tank (suggesting it is raining)

3 wait longer with waterchanges than normal and then do one.

In fact the combination of all (start of the rainy season) mentioned is best but you can try to do some stand alone.
 

ProudPapa

I try to match water temperature fairly close when doing water changes in my shrimp tanks, but I just use the finger guage (I stick a finger in the tank, then in the bucket of new water, and guage if they're close). I suspect the problem when you lost the shrimp had more to do with the volume of the water change than the temperature. I haven't been keeping them very long, but everything I've seen recommends no more than 15% at any one time.
 

DoubleDutch

BTW I always do waterchanges with cold water in my tanks. Cherryshrimps don't mind for a bit.

 

CrayfishAreAwesome

I bred my cories in 79 and the babies and cherry shrimp are living in the same tank if that helps.
 

Oriongal

I also have never bothered to temp-match when doing water changes with tanks that have shrimp, so I'd also wonder if it was a more delicate species (I only have neo's, ghost and amano), or if it was potentially a big pH difference vs. the temp difference.

I'd also say go for the 20 - 7" x 5" isn't enough room, unless you're breeding one of the pygmy varieties or something (probably not even then). There's a lot of chasing involved, and the female will also go all over the tank with the eggs before placing them (even if she just ends up placing them near the others she's already placed.)
 

LHanna61

So I've decided to keep the adults in the original tank. I've taken the heater out of their tank and (as mentioned) at the beginning of this process did a 50% water change. I think the two of those combined has created the optimal breeding parameters because they've laid eggs about 4 times in the past week. I've got close to 80 eggs and 25 hatchlings/fry.
I decided to use my empty 20 gallon for the eggs-- this way I can keep them far enough apart to avoid molding. (insert COVID 6 feet apart joke)-- this is day one of this method. I have one air stone to help oxygenate and circulate water. My plan is to suck up any that hatch and put them into the breeder box that's hanging off of my main tank.

Question for the Community: As mentioned in my first post-- I didn't expect to ever breed my Cory's so I never researched (truly) what was needed to help the eggs along. I've read up and watch numerous videos that Methylene Blue will help avoid egg rot; however, I don't have any of that.
Are there any other options? Can I treat the water with some type of medication or fin rot mixture? Would tannins be best?

Thanks!
 

Oriongal

Tannins should help, as alder cones are also frequently recommended.

I wouldn't medicate - that could get expensive in a 20 gallon. Especially when it's not really that common to lose any significant amount of eggs to fungus (in an otherwise clean, cycled tank) anyway.

Melafix/Pimafix might also be beneficial, haven't tried it myself but wouldn't be afraid to try it.

Methylene blue is good for a lot of things (besides just preventing egg fungus) and is worth keeping on hand, IMO. Best used in a container other than the tank, though; it's not safe for plants or most inverts, and can kill a cycle (BB) as well.
 

LHanna61

Oriongal thank you for your input!
unfortunately the 20 gallon isn't cycled-- it's brand new so I figured with frequent water changes it would be perfect. having said that, I only put about an inch or so of water in the tank (with an airstone). I moved all the eggs over last night and plucked out any that had mold on them (from being housed in the breeder box). I checked this morning and almost all of them are moldy now. I'm very disappointed by that. I put prime in the water and granted, the water is colder than it was in the tank-- I actually thought that would help keep any bacterial blooms at bay.
Perhaps I didn't clean out the tank well enough. but I am quite disappointed.

I'm going to let them sit as for another day. I added some Brightwell Fish Recover (with is a botanical extract that I absolutely love), I also through is some alder cones and a couple drops of BettaFix. These are the only things I have at this moment. I might put in some general cure powder just to help along any eggs that are just hours away from hatching but that's all I've got.

Anything you could provide advise on for next time? probably cycle the tank (I assume)?

Again: this was a last minute, quick-ditch effort to try and hatch eggs I hadn't intended on hatching in the first place so please don't hate on me for messing this up
 

Oriongal

Considering that I knew absolutely nothing about hatching cory eggs the first time mine spawned...I definitely wouldn't have any grounds for being critical.

You can hatch them in almost anything; a clean glass or Tupperware bowl, or a small Sterilite container. Fill with tank water, add an airstone, and heater if needed. The eggs don't have to be far apart, just not actually touching is generally good enough.

Can also put a cherry shrimp in with the eggs if you want (provided you're not using meth blue or other invert-unfriendly additive), because they will only eat fungused eggs and won't eat viable ones. (Ghost shrimp will eat viable eggs, so definitely don't use one of those.)

Shouldn't need to do water changes in the container, unless your tank water was high ammonia or something. You can put the fry in a bigger space after they hatch.

This was one of my early hatcheries - a small Sterilite, airstone, bit of cabomba from the tank, couple of alder cones, tank water, couple of pieces of Matrix from the tank filter since I was leaving the hatched fry in there for a week or so. No heater, it was peppered cory eggs/fry and the ambient temp in the room wasn't dropping below 73F.


20181107_135305.jpg

Now I put the eggs in this:


20190502_144518.jpg

It's about a gallon, a Walstad-method (no artificial filtration) nano. I don't ever save more than 15 eggs since I'm just giving them to my LFS; I'd go a little bigger if I was hatching more, because I do leave them in here for a few weeks after hatching.

This is up and running all the time, with a few cherry shrimp as regular residents. I generally get 90%-100% hatching and survival rate in this, without any additives (there often is an alder cone in it though.) Only difficulty is catching the fry when it's time to graduate them to the larger tank; they blend quite well with that substrate, and I often end up having to temporarily remove the plants and rocks to catch them as well.


20190508_102822.jpg
 

LHanna61

Oriongal
interestingggg-- I can't understand why mine are molding then.
It happens every batch of eggs, a few always mold.

Per my last post, pretty much everything I just moved to the separate tank are now covered in cloudy mold. I did have a light on overnight, so maybe that's why? I'm working on cycling a sponge in my main tank so I can start cycling this 20 gallon. I pulled another 30 eggs out of my main tank tonight but I decided to just stick those to the walls of the breeder box so I'm going to keep those in there with the 25 fry that are currently in there already. I'm just worried that feeding the fry will cause the eggs to mold-- that's why I moved the other batch (because I was seeing signs).

Do my parameters need to be anything in particular? I used about 70% RO water and the remaining was tank water. my TDS is 106 and the temp is 65. I had a heater in it all last night but turned it off this morning because (again), I was afraid the heat was going to cause the bacteria to breed and make the eggs mold faster. -- if I cycle the tank, I will for sure put some shrimp in there-- I've got it as an empty bottom with one java fern in there so they're easy to catch. I definitely don't want to destroy my main tank by putting them in there.

Attached is a pick of two clusters right next to each other. it's hard to tell so I played with the contrast but one cluster is fine and the other is coated in a cloud of mold.


How much does your LFS pay you for them?



EDIT: Upon further research, I'm going to assume the ones that are molding are unfertilized-- they aren't stark white but I looked at a few under a light and didn't see the embryo or any sign of life so I think that's safe.
 

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Oriongal

I must have missed it, but what breed of cory do you have? Can't really say that a given parameter is good or not without knowing that, since all corys don't come from identical environments.

DoubleDutch, Coradee, CoryDork (and anyone else who routinely breeds corys) may know more about why it's happening to you; I have been lucky in not having to deal with it, so don't have much experience to draw on there.

I give them to the LFS for free, along with sword and guppy offspring, and shrimp culls. There's only one non-chain store where I am, and I want them to survive; they take better care of their fish, and they always try to get in specific fish for me if I ask.

It's also a relief to me not to have to euthanize perfectly healthy fish, because I only have room to keep a few of the offspring as future breeders. So I figure I'm being compensated well enough for what I'm giving them. Might be different if I was raising discus or angels.
 

LHanna61

So sorry-- they're salt and peppers
That's awesome that you do that! Good on you!

I think it's because they aren't all fertilized-- I pulled out ones that were absolutely covered in mold and put them in a cup in the tank with some meds but I still have at least 30 in the tank that are viable for hatching (plus another 30 in my breeder box). I'll be able to tell in another two days I think. I'll just sanitize this tank more thoroughly with vinegar before I use it again. I might not have cleaned it well enough
 

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