Tombstoning (?) Cheery Barb

[Gruntle]

Hi all, I'm in the process of making an attempt at breeding Cherry Barbs. I have a cycled 20l tank with a divider, I have a male on one side and two females on the other. One female appears to be older (based on the fact she's darker) and way fatter than the other. I reckon tonight's the night for spawning (I have Barry White set up on the sound system, I've got mood lighting in mind. Nah, just kidding).
 
For the past week I've been giving a few small feeds a day of freeze dried bloodworms, they seem to love it (as do all the other fish in my main tank - it's a feeding frenzy!). But for the last two days, the fatter lady seems to be swimming normally when I enter the room, but when I go near the tank, she faces almost vertically head-down and rests her nose on the gravel.
 
Is this normal? She seems in good health otherwise. The other female and the male appear to be happy.

 

[Gruntle]

This afternoon she's resting on the gravel and no longer vertical.

 

[techen]

Test your water stats. Ammonia, nitrite and nitrates. Sounds like there's something off, normally it could be over feeding or something wrong with the swim bladder. No idea until we get some readings. Also a 20l is tiny for cherry barbs and 3 will not allow you to breed. You'll need a good group of them and a bigger tank.

 

[Gruntle]

Well, I gave up because nothing seemed to be happening in the breeder tank.  Blow me down, this morning there's a tiny little Cherry Barb in the bottom of the 200l main tank. I just hope she (I think I'll call her Valentine) finds enough spots to hide to avoid the fate that no doubt her brothers and sisters have suffered, i.e. being eaten.
 
At least I know my male is fertile!
 
And the female who I thought was doing odd things appears to have made a full recovery, although she's turned into a bit of a loner now.
 
By the way techen, water parameters were fine (0/0 ammonia/nitrite), 20ppm nitrate. I moved the trio in the 20l tank because that was the consensus on every article I researched. Now with four females and one male, they've done the job themselves (and no doubt eaten most of the offspring).  Next time I try, I might move all of the females across, not just half of them.
 
Maybe it was overfeeding that caused the odd behaviour.

 

[Gruntle]

Valentine has a twin sister and I can't tell them apart.