# How to sex Cyrtocara moorii (blue dolphins)?



## 1025667 (Dec 20, 2012)

Please give any other way besides their hump on their head. Mine are about 6-7 inches and it is hard to tell them apart right now. I have 4 but I am returning one because I think he may be a male, and I think I already have a male in the tank. Any good ways to sex them? I will post a video and a few pictures tonight! Thanks for the help in advance.

When I show you the pictures, only the 2 smaller ones and the one in the container were breed together. The largest one was not breed in that batch. Therefore size may not be the best way to tell their sex. Thanks!


----------



## 4RSo (Aug 13, 2011)

I'm thinking venting would be best


----------



## aicardi (Sep 15, 2012)

4RSo said:


> I'm thinking venting would be best


+1


----------



## Chromedome52 (Jul 25, 2009)

Anal fin shape will tell you the sexes from a very young age. If the bottom edge of the anal curves up at the back to a relatively blunt point, that's a female. If it is straight or curves down to the point at the back, that is a male. I was shown this by a Florida commercial breeder 35 years ago, selected a trio at 2.5 inches that grew up and bred for me. Hard part is getting the fish to spread the anal fin out decently.


----------



## aicardi (Sep 15, 2012)

Chromedome52 said:


> Anal fin shape will tell you the sexes from a very young age. If the bottom edge of the anal curves up at the back to a relatively blunt point, that's a female. If it is straight or curves down to the point at the back, that is a male. I was shown this by a Florida commercial breeder 35 years ago, selected a trio at 2.5 inches that grew up and bred for me. Hard part is getting the fish to spread the anal fin out decently.


Maybe, but a simple venting is 100%.


----------



## 4RSo (Aug 13, 2011)

+1


----------



## Chromedome52 (Jul 25, 2009)

Venting is not 100%, and most certainly is not simple. I've looked at purported photos of male/female vents side by side and can't see any notable difference. I suspect that it takes a practiced eye to vent. OTOH, I've explained the anal fin to many people, and every one has understood and been able to see the differences immediately. It is easier to see, and on this species, this can be considered a 100% effective method.

If it is possible to sex a fish without taking it out of the water, I consider that the preferable method. Venting cannot be done without stressing the fish and risking injury. It should be a method of last resort, not a first choice. I have never needed to vent a fish to sex it, and I am quite sure that I couldn't do it if I tried.


----------

