We have a male coral glow het pied, he was hatched in 2020, we started trying to breed him at 800 grams at the end of 2021, he now weighs 1,300.
We’ve witnessed locks, paired him multiple times over the last couple of years. One of the females is a prooven breeder.
The females have shown all the signs they were ready, including getting to the point of slamming food, but no ovulation and no eggs.
Is it possible that he is infertile?
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It’s possible. If he’s been bred recently and you’re seeing locks past that 2021 point
Unfortunately it’s something that can just happen.
I actually had issues with a small rat colony because my male ended up being infertile. And that’s a rat…one of the most prolific animals. Lol.
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Yes. It’s possible for an individual animal, any species, either sex, to be infertile.
If your male has been paired with multiple females including proven breeders, and produced no offspring, I would assume he is either infertile or has very low fertility.
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We gave him the year before last off(2023) and tried to breed him again for 2024/2025.
We paired him to 2 females this year, we saw locks(confirmed), but it looks like one of the females has already reabsorbed. The other female we did pair also with a banana pied(visual) that we thought may possibly be ready at 850 grams.
Basically he was paired with 1 female prooven breeder in 2021
Paired with the same prooven breeder and a new female in 2022
2023 off
2024 paired to the same 2 females. One looks like she’s not going to go, the other was paired to a second male and may be getting ready to lay.
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It’s certainly possible that he’s infertile. Infertility is definitely something that’s been known to occur with ball pythons of both sexes, though my impression is that it’s not super common.
Could also just be that you got really unlucky with the female not taking or reabsorbing for whatever reason. Seems unlikely that would happen two years in a row with the same male, but stranger things have happened. 
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As an aside …
There are also cases of females rejecting certain males as well. One of mine refused to lock every time with a het VPI, but had no problems with the het pied boy I tried. Lol
But that’s a different problem and an infertile/low fertility male seems more likely in this case.
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Is it possible he has been kept too warm?
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Hey. First of all, no judgment here, but are you saying you paired him to a female that was 850g? There’s no way that female is fit to breed - females can breed a bit smaller in the wild but the general weight recommendation is 1500g, and I don’t breed any females before they’re three years old and 1500 minimum. I wouldn’t even count this female in his stats as to whether or not he’s infertile, because she is definitely not ready to breed at that size.
As a second to what some other folks have said, I actually wouldn’t be too worried about infertility at this point. With a sample size of only two females that he’s been paired to, it’s entirely possible that one or both of those females rejected him/didn’t like him and didn’t use the sperm, even if they let him lock. It’s also said that ball pythons in captivity have a roughly 50-60% production rate when paired - I know plenty of breeders who pair 80+ females and only get 40-50 clutches. So at this point I personally wouldn’t be worried about infertility. It’s possible, but I don’t think it’s the most likely scenario - I think you’ve probably just gotten unlucky thus far. I’ve had many a female be paired and decide not to go.
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Oh! My apologies, I misread your post. You paired the female to a male that was 850g. Sorry, ignore what I said!
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Cool side is 75°, hot side is 88/89°
The whole room may fluctuate between 72° and 80°, but we monitor hot end and keep them steady.
5 other males in the same rack and they all breed fine.
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I understand, the proven female is over 2,300 and the unproven female just hit 2,100.
We start trying males at 600, and females 1,700 (if the female lays and drops below 1,500 they get the year off, also get every 2nd year off)
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Thank you for posting this topic, I’ve been going through the same situation with my own coral glow/butter male.
I’ve been pairing him to one proven female for 9 months, and another proven female for 4.
He’s 800g+ and readily locks with them, with me documenting multiple confirmed locks over the periods of multiple months but with absolutely NOTHING to show for it!
I’ve been checking temps and humidity for both him and my females, giving him plenty of time off between breedings.
Once my project male is up to size (which he’s almost at) I’m going to try pairing him instead- and if the girls take soon after, I really think that will prove things.
I wish I could offer some sort of advice, but short of maybe checking a sperm plug under a microscope (and even that wouldn’t tell you everything you need to know), I’m honestly not sure!
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I am annoyingly skeptical about morphs in general. We hope the mutations we love only have skin-deep effects and aren’t common in the wild only for reasons like predation but I always worry about fitness issues that are also part of the mutation itself that might carry over into captivity. I love the designer looks and want them all but always assume each new mutation MIGHT have issues until publicly proven otherwise.
In the past that public discussion has taken way too long. I produced visual caramels starting with just a possible het male before I found out about the homozygous female fertility issues. I’m not a big breeder conspiracy theorist either because while they should be the first to figure these things out and also have the most to loose from them becoming public knowledge they also have limited numbers and it’s impossible to be sure that just because you have seen an issue a few times it will always be an issue. But ultimately any issues will eventually come out and delay only spreads the pain.
I’m wondering if software like CLTCH or Husbandry Pro could help anonymously aggregate morph data? Would those companies and their users be ok with a report like “as of X date we have Y recorded breeding attempts for Z morph males of average age 18.9 months with a success rate of 5.2% validated by offspring set up within 12 months after pairing”? All kind off stats like age to breed and good egg rates could be compiled for each gender of each morph. With genetic testing tie-ins it could be really accurate on any het effects too.
In my small collection I have tried to breed 6 males het for DG but only got eggs from 3 of them. All were young males and paired with a limited number of females. Could well be bad luck or poor conditioned females in my small sample size so I really can’t be sure that the three fathers also being het DGb and the three no eggs not being het DGb means anything. But, if we had data on 100 or 1,000 het DG (ie DGc) males from a widely used tracking software we could start to see or refute a pattern.
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I do also think that people severely underestimate the number of times females just decide to reject a male. In the wild, there are any number of sexual selection criteria that the females may abide by - anything from size, appearance, smell, pheromones, behavior, etc. that females may take into account when selecting a mate. In captivity, we just put two snakes together and expect them to mate. And while it does seem to happen that they’re compatible a good portion of the time, I think it’s a completely reasonable assumption that sometimes female just don’t like a male and will choose not to produce eggs. This is why I more often pair two males to one female (where I can tell who the father would be based on the genetics of the babies) and have had pretty good luck with this.
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I think there is a lot of precedent for females (other species, including humans) being able to detect and select for complimentary immune system components in potential mates. Some pairs really don’t seem to like each other and maybe those are cases of some sort of incompatibility. But, I’m several cases my males were allowed to mate, often, just didn’t produce eggs.
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Like others in this discussion.,I have had both multiple matings with a specific male and no result and Females rejecting males whatever I do and then mating every time offered with a different male.
Thats been covered but, I heard an interesting theory about non compatibility from one of Gavins (ball2you) videos. Its just a thought but he suggests we don’t know the location origin of our animals and like the origin can have an effect on size, maybe it has an affect on compatibility.
Even with mixed origins an animal can have more DNA of a particulate location. Maybe it creates slightly different pheromones.
Whatever is the cause compatibility is a thing.
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Very good point. Maybe ball pythons have subspecies?
I have one girl still from back when most of the pet store babies were imports (2004). I’ve only gotten 1 clutch from her tan over two decades now. Maybe her odd look isn’t a potential new morph but just normal from some locality she was smuggled in from.
Riffing off this, sometimes it is just the male and your environment. I had a male that I paired with six different females over four years and I got nothing from him. Sent him to a friend with that caveat that I thought he was a dud and the twit sired three clutches that season… Sometimes the cosmic dice just do not fall in your favour
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Given the fluidity that we see in the intrabreeding between subspecies levels of other pythons (retics, carpets, chondros, STP…) and also the relatively high rate of hybridization from highly ancestrally divergent genera (walls, burm-balls, superballs, carballpondros…) I find it difficult to believe that locality populations of balls would have fertility issues
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Some more food for though… When you have been doing this long enough you begin to notice that there seem to be cycles across the entire hobby where some years everyone produces fewer clutches than expected. Or have a later season than expected… If you are holding tight and fast to the “normal” schedule that is posted by people instead of learning the rhythm of your collection, you might be missing the window of your specific animals. Have you palped your females to see if they even have follicles??
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