Next Time in Breeder Tank. Help telling male from female

[gwand]

I have 6 Anomalochromis thomasi sharing a tank with 6 Alestopetersius caudalis and a widowed Pelvicachromis pulcher female. One pair of thomasi have fry this morning but in this tank with many hungry fish, their survival is in doubt. I am cycling a breeder tank which will be ready by the thomasi next spawn. Unfortunately I cannot tell male from female thomasi so picking a pair for the breeder tank will be difficult. I could put all six thomasi in the breeder tank and remove them all when fry are present. Anyone know how to distinguish male from female thomasi or have other ideas? Here are the parents

 

[GaryE]

What I did with mine is watch very closely to identify the pair as they guarded. Then I tried to catch those two for the breeder. The breeding tubes are different, but the sexes look extremely similar until they get older, at which point the dorsal tips are more developed on males, but a tiny bit.

I have one I am convinced is female after keeping the species for 2 generations in the past, but I'm not sure why I think she's a she.

 

[gwand]

The larger fish of the pair does have a more extended dorsal fin. Plus, it is definitely larger than the mate. Both fish are vigorously guarding the fry. I leave for a week tomorrow. All of the fish will become hungry, and I do not think the fry will have a chance. When it rains, it pours. In addition to these fry, I have a. cacatuoides fry and golden sailfin Molly fry that will be struggling to survive. It’s a cruel world. I can’t wait to use the breeder tank and enhance survival statistics.

I turned the lights up, which I rarely do to mitigate any algae problems, and all of the fish look amazing. It is a really beautiful tank. Thanks for your guidance.

 

[Mr Limpet]

The fish on the left is the male. Even young males have much more of the violet spangles on their sides than females . Fully grown males are substantially larger than females. If the tank is densely planted it’s possible that some fry will survive.