Determining the sex of difficult-to-identify fish

[bettaMagenta]

I don't breed often, but I'm currently raising my own Tilapia fingerlings for next spring. On my larger fish that I harvested this fall, I didn't do a great job sexing my breeders and ended up with extra males fighting over a single female.

From what I've learned, sexing Tilapia involves examining the fish - those with two vents are female, while those with one vent are male. It's impressive that distributors can sex them at the fry stage. For smaller fish, I've read that using a cue tip with blue food coloring and swiping it over the vent area can help. A magnifying lens would likely make this process easier.

I believe this physical trait applies to all egg layers - they should have two vents. Live bearers, on the other hand, usually have a specialized fin that's used for impregnating the female.

I'm curious about other species, like angel fish. While they would require handling, I assume the same dye method could be used to determine their sex.