when will you be able to tell male from female, in blue dolphin cichlids, x?

Question

at what age, x

Answer 1

I have 6 blue dolphins in a 20 g growout tank and they are starting to show sexual differences now at about age 8 months. The males (3) are starting to show pronounced humps on the head and are much more blue than the females.

There is one that will be the dominant male (4 inches), he is larger than the other two (<4 inches). The agression level at this point is just minimal chasing, but soon I will have to remove the two sub-dominant males to save their lives.

Another couple months and I will have to move them to a larger tank too. They will need at least a 40 g to house them properly.

I hope to get a nice breeding group of 1 M and 3 F from this group. They sell very well at the fish club auctions in my area.

If yours are at least 3 inches long and look almost identical, you probably have either 2 males or 2 females. Females would be good, then you can just look for one male to add to the mix and have a small breeding group. Add another female or two to minimize the harrassment from the male.

Answer 2

Not for a while - as they begin to reach a more mature size of 5-6 inches you'll be able to tell by the superior size of the male, and you'll find the behavior of the males more aggressive. There is no guarantee though, and since you have only two of them it will be even tougher, as a dominent male will get aggressive toward females or other males, and will likely outgrow a second male.