Who Gives A Fish Forums

I was reading about pH levels and sex determination in fry, and it seems if the tank pH is above 7, all the fry will be male, while below 7, they'll all be female. My tank's pH is 7.4, so I'm wondering how sensitive this is - will I get all males or can I still expect some females since it's not drastically above 7. Also, what's the best approach for raising the fry - should I leave them with their parents to grow naturally, or separate them into their own tank for better care?

Having a pH at one extreme or the other won't guarantee a single-sex population - that would be unsustainable for the species. Instead, you can expect a majority of one sex, but both should still be present.

As for rearing the fry, removing the male is the recommended approach. This method yields better survival rates for the fry, as the female provides essential care, guiding them to food and safety. The reason for separating the male is to prevent potential aggression from the female, who becomes fiercely protective of her young. However, if the tank is spacious enough, this risk is mitigated, allowing the male to avoid the spawning site.

Thanks for clarifying, I appreciate that. I was just pointing out that it's not unheard of for certain species to only produce one sex, like tortoiseshell cats for example. They're always female and if a male is born, he's sterile, so it's not entirely impossible for that to happen in other species.

I was also wondering, would the male try to harm the female if he thinks she's not doing a good job of taking care of the fry?

I personally keep the male and female together, then I remove a large portion of the fry once they're free swimming - about 75% to be exact. My current batch in the grow-out tank has both males and females, and I did use Seachem Neutral Regulator pH when the eggs were laid.

I was wondering if kribensis always spawn in the same cave, or if they tend to mix it up a bit. Also, would they spawn in two different caves at the same time, or do they usually stick to one spot.

I think you're getting your wires crossed with the tortoiseshell cat thing - that's a result of selective breeding for color, not a natural occurrence. They've essentially sacrificed some reproductive genes for the sake of aesthetics, which is why they rarely produce males and even then, they're usually sterile. In the wild, you'd never see this kind of thing happening with wild cats, it's just not how nature intended it.

I've had mine spawn in the same spot every time, but I suppose they might use a different one if they feel it's safer. As for spawning in two caves at the same time, I'm not really sure, but I've never seen it happen with mine.

Thanks for the info, I was just curious because I put the pot back in that the female spawned in the first time, but they've cleared it out now and started clearing under my PVC pipe instead - is that a normal thing for them to do? Also, I've got platys in with the kribensis at the moment, but I'm thinking I might need something a bit faster to keep them company, any suggestions for good tankmates?

Considering your tank size and the fact that you're already housing platys with the kribensis, I would recommend sticking to a single species setup for optimal results. The kribensis seem to be doing well with the current arrangement, and introducing faster fish may disrupt the balance you've established.

I tried it without any tankmates and my kribs started getting aggressive with each other, but once the platys were back in, they went back to their usual flirting. I was planning on removing the platys when the fry hatched, but it seems like having them in there is actually helping to reduce aggression between the kribs.