Only males in the fry

[fideltagamma]

Hi

I have some friends, who breed apistos. Lately they ran into a huge
problem. The whole fry became male. It happend to A. atahualpa, and A
sp. "Rio Mamore" (or A. maciliensis according to Römer).
There were no females and nothing happend when they adjusted PH or
other water conditions. This happend now for twice or three times. So
what did go wrong or what can they do to have females as well?

FiDeltaGamma

 

[farm41]

most likely the temperature was to high. What is the temp. of the tank, and the Ph?

 

[fideltagamma]

I think pH was between 5.5-6.0. Though I have no information on the temperature.

Thanks for the answer.

fideltagamma

 

[Neil]

fideltagamma,

WELCOME TO THE FORUM

I am of the belief that there are more factors involved in gender determination in apisto fry than pH and temp. IE, minerals and other substances in the water, tank inhabitants (especially other apistos of similar species), which spawning it is (first is quite often different, given similar parms), how old both the male and female are, etc.
That said, I think that the most relavant issue here is probably temp. related to pH. If your pH is low or high, the temp. can play a significant role in shifting the ratio. If it is necessary to get a spawn with a low pH, then the temp. can be slowly altered after the spawning to help equal the ratio, because it is likely that sex can be determined weeks after spawning.
It is impressive that they spawned atahualpa in the first place. I consider it one of the toughest apistos to breed.

Neil

 

[fideltagamma]

Thanks for the welcome! Though I'm new for the second time.

Well it's quite surprising for me, that gender is determined in lots of weeks after spawning. I thought that sex is determined until the fry swims free.

Thanks for your answer.

FiDeltaGamma

 

[Neil]

Thanks for the welcome! Though I'm new for the second time.

Yes, I kind of knew that, but I am just going to go through my normal little welcome deal with anyone who is new, even for the second time. We lost your posts and membership, we should welcome you again!

Well it's quite surprising for me, that gender is determined in lots of weeks after spawning. I thought that sex is determined until the fry swims free.

Yes, that is pretty interesting, isn't it? I am not sure how long after "birth" the window is, but probably as much as 4 or 5 weeks. Again this is even more time for various influences to play a role in gender. I would be curious to know, for example, whether the sex ratio would be different if half newly free-swimming fry were placed in harder, mineral rich water and the other half in softer, mineral poor water, given that all other conditions were identical. Or if a spawn from a particular species were raised in a harem situation (with 1 male and many females in the area). And then that female were to be placed in a situation where there was numerous males and only her.
Temp. has definitely been found to alter ratios, but to what degree, I am not entirely sure. If they were bred at 80 and kept at 80 for 6 weeks, would there always be the same differences in the ratio with different species and in a multitude of different situations. I don't think so. At least, I have not found that to be the case. It is not nearly as black and white as that. For many species, I have found that breeding at 80 to 82 degree with a pH of 6.0 (and low hardness) and then maintaining a temp. of 77 to 78 for a month or so after has proved to be pretty reliable. But, I have certainly had my disappointments with that formula too. I have had even sex ratios from certain species at 83 degrees, ph - 4, no hardness and from other species at 76 degrees, pH - 7.3, mostly tap.
I am kind of happy for all of the little roadblocks to getting, IDing, keeping, breeding, and raising Dwarf Cichlids. If it were really easy, it wouldn't be nearly as interesting and everyone would be doing it. This forum wouldn't be doing as well as it is either .

Neil