Matt Kaufman
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One thing to ensure is that you keep track of each egg; many a time fry eat each other, so you pick 50 eggs, 20 hatch, 8 make it to juvenile of which 7 are males, ergo, skewed. Not necessarily. If you start with 50 eggs and end up with 50 juveniles that are 90% male, yes, that's skewed.
As Jim's pointed out, environmental factors can matter like temperature and pH. There's really no one answer. Some fish are great - 50/50 with no effort. Most are skewed one way or another. There's no one-size-fits-all answer.
Another 'old time' trick I used once with a really skewed fish (A. ogo. ottogartneri) was raising eggs in pairs in ice cube trays and raising the fry separately. Ultra-tedious, but successful, got 50/50 mix. Anything beyond like 20 pairs was too much, though. I raised them in separate containers to adulthood, kept a few pairs of breeders that did yield better results in the offspring - still not 50/50 but more like 70/30 which was more suitable for breeding in big groups. Weirdly, after a few generations, the split went about 60/40 females. There were enough of us keeping that fish that we could swap males for females and we kept the line going for some time.
Some fish are really bad like Lamprichthys. 100% one sex is not uncommon. In fake lake Tanganyika water with careful attention to eggs and fry I could get about 1/3 females which kept me going. Some locals couldn't get females at all even starting with wild pairs.
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