How long to keep Corydoras sterbai in the breeder box?

[Rube_Goldfish]

I use the Ziss Premium Breeder Box inside a ten gallon fry grow-out tank. At the moment, the tank has three approximately one inch (2.5 cm) total length Corydoras sterbai juveniles from a previous spawn and two at about 3/4 inch, who all get along just fine. The one inch fish are ready to go to my LFS, but I am just sort of waiting for the other two to catch up, so I can bring all five at once.

The breeder box has between 20-30 fry, the longest of which is maybe just at the 1/2 inch mark (very approximate; I'm just trying to eyeball them). I'm pretty sure if I released them from the box into the tank that they are now too big for their older siblings to bother them, but I'm looking for reassurance.

I'd also like to know at what point do you think the benefits of being housed in a breeder box are outweighed by the drawbacks? That is, when do you transfer your fry from the box to a grow-out tank?

Thanks in advance!

Edited June 25 by Rube_Goldfish

[GoofyGarra]

I do not have experience with Sterbai cories, but I've bred a lot of Albino Cories which are a pretty similar species.

Personally I would catch out the largest of the fry in the breeder box and add them to the tank, and keep the smaller ones in the breeder box. This will allow the larger cories to get more room to grow without being food competition for their younger siblings.

[Maximus]

If I was in your situation, I'd wait until I caught and sold the ones destined for your LFS before adding more to the grow out tank, purely because it'll make it easier to catch them without having a bunch of extra fish in there to navigate around.

[tolstoy21]

On 6/25/2024 at 9:33 AM, GoofyGarra said:

Personally I would catch out the largest of the fry in the breeder box and add them to the tank, and keep the smaller ones in the breeder box. This will allow the larger cories to get more room to grow without being food competition for their younger siblings.

This is what I do with my Sterbai. I use two of the Ziss hang on breeder boxes in rotation. One has younger, smaller fry; the other, older larger fry. When the fry in the 'older' box are large enough to go into the grow out, I dump them out, clean out the box, and start anew. (The 'younger' fry box now becomes the new 'older' fry box if that makes sense).

On 6/25/2024 at 9:17 AM, Rube_Goldfish said:

I'd also like to know at what point do you think the benefits of being housed in a breeder box are outweighed by the drawbacks? That is, when do you transfer your fry from the box to a grow-out tank?

I try to move them out as soon as I don't think they will get eaten. I find the longer I keep fish in breeder boxes, the greater the chances I have of losing them.

Edited June 26 by tolstoy21

[Guppysnail]

On 6/25/2024 at 10:20 PM, tolstoy21 said:

try to move them out as soon as I don't think they will get eaten. I find the longer I keep fish in breeder boxes, the greater the chances I have of losing them.

This is solid advice. I’ve also found corydora grow at almost twice the rate being free range vs kept in breeders. 

[Rube_Goldfish]

On 7/10/2024 at 7:52 AM, Guppysnail said:

This is solid advice. I’ve also found corydora grow at almost twice the rate being free range vs kept in breeders. 

I haven't been scientific about it, but I believe it. I released them from the Ziss breeder box into the 10 gallon grow-out tank the box sits in on June 26 (the next day after getting @tolstoy21 's advice). They look like they're half to 2/3 of an inch already (but take that with a grain of salt; they refuse to swim past a ruler).

[Rube_Goldfish]

One thing I'll say though, thinking a little more about this, is that when they were in the box, I could see exactly how much food remained. My fry grow-out has a thin sand substrate, a couple of epiphytes on small wood and rocks, and scattered lava rocks (plus some floating plants). That all means that it's more guesswork to know how much they're eating and how fast, but I still think it's worth it because they get more space but also access to whatever microflora and fauna are living in the tank, which has been running continuously for about 2 years.

But like I said, they seem to like it.

[Guppysnail]

On 7/10/2024 at 9:03 AM, Rube_Goldfish said:

One thing I'll say though, thinking a little more about this, is that when they were in the box, I could see exactly how much food remained. My fry grow-out has a thin sand substrate, a couple of epiphytes on small wood and rocks, and scattered lava rocks (plus some floating plants). That all means that it's more guesswork to know how much they're eating and how fast, but I still think it's worth it because they get more space but also access to whatever microflora and fauna are living in the tank, which has been running continuously for about 2 years.

But like I said, they seem to like it.

They need less than what we think. A lot less. 
I made this a bit ago for someone. It turned out there were 60-70 Aspidora  a few melini and a few Pygmy in here. This is all I fed them 3x a day up to the point they could eat white worms then feeding dropped to 2x a day. I would squirt this much fry food am. Lunch was bbs the this fry food for dinner. At our club auctions and swaps my fish are known as growing big fast. 
Excess food causes their body to work harder to defend from pollution caused by decaying food.