CA Cichlids -- Are Males Rare?
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Posted this a while back, can get you the full link if people want
female cichlid held in isolation has managed to self fertilise herself and produce offspring.
The cichlid, living at Hull University, was an experimental cross between two species: Pundamilia pundamilia and Neochromis omnicaeruleus.
She was kept in a tank on her own, like dozens of her siblings — but despite the lack of a mate, she still managed to produce more than 40 youngsters over a two-year period.
This is known as ‘selfing’ or self fertilisation. It’s a fairly common method of reproduction among flowers and insects — but in vertebrates it’s very rare.
The Mangrove killifish (Kryptolebias marmoratus) is one of the few species known to self fertilise. It’s thought to have developed the ability as finding a mate isn’t always easy and selfing is better than not reproducing at all, despite the obvious inbreeding risks such a method poses.
The reason for the selfing in the hybrid cichlid — the only one of 80 similar hybrid females to do so — is unclear, but it could be a genetic 'innovation' caused by the hybrid nature of the fish, due to its parents having different sex-determining genes, say the researchers.
The fish was a mouthbrooder, and she reproduced by fertilising eggs held in her mouth with the sperm she released into the water and then sucked up.
Seventeen of the 40-odd youngsters she produced grew to adulthood. These fish were also kept in isolation but while they were fertile, none of them exhibited the same selfing ability. However, these offspring all suffered from what scientists call ‘inbreeding depression’ — minimal genetic diversity, which can lead to birth defects in subsequent generations.
On dissection of the selfing female, it was found that she had developed sperm-containing tissue — a testicle of sorts — next to her normal reproductive organs.
The study was published in the journal Royal Society Open Science.
female cichlid held in isolation has managed to self fertilise herself and produce offspring.
The cichlid, living at Hull University, was an experimental cross between two species: Pundamilia pundamilia and Neochromis omnicaeruleus.
She was kept in a tank on her own, like dozens of her siblings — but despite the lack of a mate, she still managed to produce more than 40 youngsters over a two-year period.
This is known as ‘selfing’ or self fertilisation. It’s a fairly common method of reproduction among flowers and insects — but in vertebrates it’s very rare.
The Mangrove killifish (Kryptolebias marmoratus) is one of the few species known to self fertilise. It’s thought to have developed the ability as finding a mate isn’t always easy and selfing is better than not reproducing at all, despite the obvious inbreeding risks such a method poses.
The reason for the selfing in the hybrid cichlid — the only one of 80 similar hybrid females to do so — is unclear, but it could be a genetic 'innovation' caused by the hybrid nature of the fish, due to its parents having different sex-determining genes, say the researchers.
The fish was a mouthbrooder, and she reproduced by fertilising eggs held in her mouth with the sperm she released into the water and then sucked up.
Seventeen of the 40-odd youngsters she produced grew to adulthood. These fish were also kept in isolation but while they were fertile, none of them exhibited the same selfing ability. However, these offspring all suffered from what scientists call ‘inbreeding depression’ — minimal genetic diversity, which can lead to birth defects in subsequent generations.
On dissection of the selfing female, it was found that she had developed sperm-containing tissue — a testicle of sorts — next to her normal reproductive organs.
The study was published in the journal Royal Society Open Science.
Idk about the numbers but I get males of most fish i buy... When i was trying to breed Texas i went through about 15+ fish, grew them to a size when i thought i could sex them and they wouldve started at least courting if bot breeding... Not a one had a dorsal spot or started to court... All males... That pissed me off.
It's not a common occurrence by any means. The except can be found in Barlows book: The Cichlid Fishes. Natures Grand Experiment in Evolution. If you google you can see a few references to it as well.
I have also had a similar thing happen. When my Alcolapia alcalicus spawned, one group of fry ended up to be all females (I believe it was because the water was about 5'F too cool during spawning and rearing (Lake Natron is normally 90'+F)), after the male parent died and all those females had been adults for an extended period (even spawning with the adult male/father), one of the females changed over, and became male, and spawned with a sister.
The shots below is of two sisters spawning, after one became a male.
The shots below is of two sisters spawning, after one became a male.
I've had a similar experience with swordtails.
Almost all the fry from my first few batches turned out male or late developing males.
I was told it was due to not giving enough meaty foods for the first few feeds.I have no idea if that was the reason or not.
The latest fry I have given more meaty food rather than crushed flakes and pellets. At this point the fry are still to small to tell if this made any difference.
Almost all the fry from my first few batches turned out male or late developing males.
I was told it was due to not giving enough meaty foods for the first few feeds.I have no idea if that was the reason or not.
The latest fry I have given more meaty food rather than crushed flakes and pellets. At this point the fry are still to small to tell if this made any difference.
I started a Festae breeding project recently and at one point I acquired 14 juveniles from the same source. I'd say 5 of those are male. Seems to be a ratio I've seen for Festae in the past. I now have 24 total at anywhere from 2-4" and there is probably 8 or 9 males in there.
I started a Festae breeding project recently and at one point I acquired 14 juveniles from the same source. I'd say 5 of those are male. Seems to be a ratio I've seen for Festae in the past. I now have 24 total at anywhere from 2-4" and there is probably 8 or 9 males in there.
uh huh....see, right there. So I just started a breeding project with 8 2 inch fish, and if they are at the same ration you have with Festae, I'd be lucky to have 1 or 2 males. My luck, one will catch duck lips, and I'll be left 6 females.
This is exactly what I'm talking about. I'm thinking starting with 8 wasn't enough. I might order another 15 just to be sure.
I get the feeling, especially with Herichthys (like cyanoguttatus or carpintus) gender ratios can be skewed because they are kept too warm, I had no trouble with ratios, and I keep them at high 60/low 70 temps. These species are from northern Mexico (carpintus), and Texas and there are seasonal changes where temps can be lower, even into the low 60s"F.
Beanii are also from the north western slope of Mexico, and why I believe they were very comfortable in high 60s, low 70s. In fact when I had a summer heat wave, they became subject to bacterial infection.
Beanii are also from the north western slope of Mexico, and why I believe they were very comfortable in high 60s, low 70s. In fact when I had a summer heat wave, they became subject to bacterial infection.
