Prevent sex changes between spawns

[aellis9369]

I’m planning to get into marine breeding, and have a question about fish sexes. I wanted to try neon dottybacks and centropyge argi, but both are fish that don’t pair well (according to the internets) and would change sex if left alone too long…so any clue how to keep my females female when they are put in a different tank between spawn attempts?

 

[Rocks reef]

I would assume you would have to keep them separated individually.

 

[b1llvance]

I don't know about the dottybacks as I've never worked with them but with the Centropyge, you shouldn't be separating them between spawns. As far as I know that doesn't benefit them in any way. Once you have a pair or trio established them them in the same tank. Pairing Centropyges is easy to do and once a pair or trio forms they will co-habitat in the same tank indefinitely just fine.
The main problem with reintroducing them constantly would be aggression from the fish that is already at home in a tank and the new fish being dropped into a situation where the "Home" fish already has a territory set up. Doing that over and over is a recipe for disaster. Even if it doesn't result in bullying to the point that the "visiting" fish is killed, you are certainly slowing down how long it will take for them to spawn and most likely shrink the size of the spawn as well. As Centropyge spawn over and over their spawn size begin to grow. I fear pulling them constantly would just set this back each time, and you would forever have small egg counts.
The easiest way to pair the two is to get a large and small fish, and introduce them at the same time. If one is already at home in the tank and you have the ability to remove it for a bit you should do that and reintroduce the fish together. If you can rearrange the rock in the tank that would be even better. A large and small fish will work out who is female and male real quick and the chasing will subside in short order. You can also do two small fish but chasing will continue for a bit while they work it out and that could lead to injuries but if the tank is large enough and there are enough hiding spots you should be fine.

 

[b1llvance]

Just to let you know, I’ve had success this way, and I’m not just talking, here are my flames and a trio of potters kept recently.
View attachment 20250929_104803_AA5A3B17-1059-429C-8B49-D94CEE5029FB.mov

 

[b1llvance]

Finally here is a great paper about the harem structure of Centropyge and how to pair. It also references another study done that says a female kept by herself may need the presence of another smaller female in order to initiates its transition to male. Meaning a single female will stay female in a tank. This study references 100 days as its time duration so maybe it does happen it just takes longer to transition than if in the presence of a small female.

Harem structure of the protogynous angelfish, Centropyge ferrugatus (Pomacanthidae)

Social structure of the protogynous angelfish, Centropyge ferrugatus, was examined on the coral reefs of Sesoko Island, Okinawa, Japan. Each individual male monopolized a harem of 1-6 females. Harems could be categorized as linear-type or

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