I have 3 labs in a 55, one is stacking gravel pieces upon one of the aquarium rock decorations and may also be fin nipping the smallest lab. I have not really been paying attention and cannot confirm if its the biggest one doing both the rock stacking and bullying but if it is can anyone deduce the sex of the 3 yellows labs in the 55 gallon? I'm guessing its 2 males and a female but I'm new at this, please extend your expertise to help me better understand what is going on and how to prepare for breeding if it is to occur. They grow pretty ****ing fast!
I would assume your largest one is stacking the rocks. The males make the territory. I have been told multiple times how difficult it is to tell these fish apart. I have not vented mine.
However, my 100% male is the largest. He has very black fins on the top and bottom and is highly aggressive to every other lab. He chases all of them. We used to joke that he didn't understand the females wanted nothing to do with him. They literally go parallel by the filter intake or heater so he doesn't "bother" them. Male yellow labs are quite abusive with mating. Seems our one female eventually gave in. The male also dances for the females. A display of shaking. It is quite amusing.
The issue with going by color is apparently the females can have some black on the bottom fins as well. Our next largest yellow lab, we are not 100% sure. Definitely whiter fins on the bottom; however, has not had eggs. The coloring is a tad more black on the bottom then our 100% female. The 2nd smallest one is 100% female. She has been doing the egg carrying. She does have all white on the bottom fins only. No hint of black. When we bought a 4th yellow lab last weekend, we could have opted for a higher price for a female that was carrying eggs in her mouth. I opted to go for the smallest fish with the whitest bottom fins I could find. Again, not a guarantee; however, has mostly worked for us. Since this species are all basically the same color, we have not bothered with the venting.
Our female should have the fry hatching soon; however, we have not successfully had babies alive. I feel the filter and the other fish in the tank are probably getting a free meal. If you do actually want to breed them on purpose, I would get a smaller tank with rock work and stick the female in there once she has been carrying the eggs for like a week. As far as the after hatching, that would have to come from someone else. I have heard that you do want to keep mom with the fry for a week though.
The female will have the eggs in her mouth for 24 to 30 days. Our female doesn't eat when she is holding the eggs. She will seldomly get a piece of food off of the sand if the other fish are not around and then go into a cave. So, it does stress them to a degree, which is partly why the harem ratio is important along with controlling male aggression.