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Hi all,

I am trying to spawn corydoras sterbai. This quest started 8 months ago, but no success so far. I have read a lot of success stories and compiled a few ideas but I canâ??t figure out whatâ??s wrong.
Here are the details, so you can try and give me some suggestions or advice.

The setup:
- Tank 60cm*30cm*40cm (23.6in*11.8in*15.7in)
- Volume 72ltr (19g) / water volume used 60ltr (15.9g)
- Silica sand bottom, like the sand on a beach. White.
- Java moss in small driftwood.
- 2 half clay pots for hide out.
- Natural light, dim.
- Filtration eheim 2224 (700l/h) â?? (185.2g/h)
- 150w thermostat
- 14 specimens (wild). Average specimen lenght 5cm (2.2in). I don't know how many males/females.

The food:
- Morning: hikari pellets + (every other day between sera discus morsels and nutrafin shrimp pellets)
- Night: every other day between frozen artemia and frozen mosquito red larvae.
(All generous quantities)

Normal parameters:
- pH 6.2
- Ammonia 0 ppm
- Nitrite 0 ppm
- Nitrate 5-10 ppm
- dH 1º
- 28ºC (82.4ºF)

Daily â??modus operandisâ??:
- 2 feed per day. One in the morning, other 14h later.
- 60% water change at night(before last meal) with bottom siphon (at 18ºC â?? 64.4ºF). (75% osmosis â?? 25% tap )
- After water change, tank temperature is 24ºC (75.2ºF). It takes 3h to get to 28ºC (82.4ºF) again.
- Every 10 days I make 70% water change 100% osmosis (at 18ºC â?? 64.4ºF). (I keep for 5 more days 100% osmosis, then back to normal water change (75%-25%) for a month)
- Once per week I put 12 drops of eSHa-optima.

All suggestions, ideas or opinions are welcome.

Thank you all,
Gul

Firstly I think that there will have been some spawning activity, but because of the number of fish in the group those that were not involved in spawning would most certainly have been seeking out and eating eggs.

I would be inclined to set up a slightly smaller breeding tank with the same sand substrate, some Java moss and may be a couple of floating spawning mops and a large sponge filter.

Add a trio of adults (2 males, 1 female). Make weekly 50% water changes with the same temperature water. Feed as you are doing now, give them a month at this regime and then give a 70% water change using water 7 to 10 degrees F. cooler.

I actually run a group of 5 (3m & 2F), and the have been spawning pretty regularly for the last 15 years.

Ian

Ian is "the man" when it comes to breeding Corys. Follow his advice.
I would add all the live worms they can eat to their diet. It is amazing what they can do when it comes to breeding Corydoras.

Hi,

I will follow Ian's advice. I have one of his books, quite a bibleâ?¦ not as much detail has I need, but very good.
Concerning worm feeding, I can give them some frozen worms. My live grindal stock is very low. (Ant attack)

Well, thank you both for your assistance, I will give newsâ?¦

Gul

First of all, I would add some "sexual booster" to the food - earthworms, tubifex or beef heart. My sterbai often spawn spontaneously after 4-5 weeks of such a feeding. Or I stimulate them by 30-50% water changes every other day coupled with drops of temperature. Sometimes they spawn very eagerly after mere 5 months since the last spawning period, sometimes they refuse to spawn and it takes more time. But the problems may be elsewhere, of course. For example, my first sterbai that I bought (5 pieces) refused to spawn for many years, and eventually I found out that I had bought five males.

Spawning wild fish is naturally more difficult than spawning F generations. If you don't succeed, you should rather buy some F-generation. The fish may have been namely "cured" in some salesmen, and according to some people, it can lead to infertility.

14 pieces in a 72 liter tank is really too much, but they don't eat eggs, if you feed them really heavily. I myself have 23 adult pieces in a 130-liter tank and they used to eat almost all eggs. Hence I started to feed them very heavily, twice a day, during the spawning period, and they don't eat them anymore. I have even recorded as much as 380 eggs during a mass spawning.

I have exactly the same experience. Therefore I maintain a constant supply of blackworms in my breeding setups. This is also a clean food because they stay alive until eaten. I also make sure that the breeding tank contains no snails that might eat the eggs. I find this advantageous because the cleaner the water the less of a problem I have with fungused eggs, egg eating and a higher survival rate among the fry. I find them to be very sensitive to pollution of any sort during their first two weeks. That is why I use microworms for their first food as they stay alive and on the bottom where the fry can easily find them. I begin using more live baby brineshrimp, powdered flake foods and cyclopeeze after two weeks and on.
Prior to setting my Corys up in their breeding tank I feed them earthworm flakes and pellets in addition to live blackworms and frozen bloodworms. I often add a mystery snail to the hatched fry tank to help clean up any uneaten or dead food. Mystery snails do not over run your tank with a zillion snails as will Physa, the common pond snails.