Strange Pink Bump On Angelfish?

[Mr Melt]

Hi all. I recently bought 2 Longfin Angelfish for my 200 litre tank. Instore I asked if they were sexed, to which they said no.

Regardless they have been swimming happily in my tank to date.

However not 10 minutes ago I noticed a small pink bump in between the ventral fins on my black angelfish - I'm quite concerned; is this normal, as I have not seen it before =(

 

[Mr Melt]

And now the bump has disappeared......

After a bit of research I've discovered that the bump is its papilla, which is only really visible when the fish is either laying eggs or fertilising said eggs.

Why is it though that only one's papilla was showing? Why not both? In addition, I have searched the tank and I couldn't find any eggs =/

 

[minnnt]

It's just something they do from time to time. If it was thin and pointed then it is a male, if it's thicker and less pointy then it's a female. it's usually a sign that one has took a shine to the other especially if there is no aggression between them.

 

[Mr Melt]

It's just something they do from time to time. If it was thin and pointed then it is a male, if it's thicker and less pointy then it's a female. it's usually a sign that one has took a shine to the other especially if there is no aggression between them.

They're always swimming together; the papilla seemed to be quite thick and pointed in the corner (slightly). Does this mean that I have a mixed pair in the tank then? If so then brilliant; what are the odds of that happening (especially as I only picked 2 at random) =D