Obese Tetra - What Action?

Hi folks,

As mentioned in another thread earlier in the week:
One of the two female tetras, the one which eats a huge proportion of the food, has been getting increasingly large of late - so much so that she now resembles a fancy goldfish, rounded on both "flanks" when viewed from behind and with her face almost hidden in her body. I may have to consider isolating her - not something I'd wanted to do but I can't see an alternative. [http://www.thinkfish.co.uk/forums/general-fishkeeping-chat/think-fish-keepers-daily-news/160/#sthash.fTfQ03TN.dpuf]

The fish are fed a mix of flakes and pellets twice daily, with chopped peas twice per week, but this particular female has amazing tank coverage and somehow manages to reach the majority of food for herself, with the two female tetras tending to be the only two which forage in the substrate for leftovers.

I'm attaching some photos of her here and would appreciate some advice on whether this is at the stage where some concerted action needs to be taken, such as isolating her and cutting back on food? I'm reluctant to do this as she's behaving completely normally and I'm concerned that isolation in a QT may have a negative impact on a happy, otherwise-well, shoaling fish. Thoughts welcome; thanks.

NB. Second pic is view from directly behind - she's in front of the base of the silk plant, so it shows how large/bulgy her flanks are on each side when viewed from behind, round like a ball and similar to a fancy goldfish. The other, normal-sized female is above her.

Really? Wow - I thought she was on the verge of exploding. That's helpful to know; thanks.

...Kinda looks like a micro Great White Shark   

Isolation might not be a bad thing to my mind - my neon tetras are like Hoover's when there's food about and they often spit it back out again when they realise they can't "swallow" it all in one go.

No!!!!! The missing male tetra has been found, inside the back of the filter bracket.    This must have happened during yesterday evening's water change.  Furious with myself that I've inadvertently killed a perfectly healthy fish, judging by how colourful, happy and active everyone has been.

I should have dismantled the filter bracketing last night to check, but everyone had settled down for the night at that stage and I thought best not to disturb them.   Perhaps I could have saved him, had I made this discovery last night. 

Argh - I'm distraught and angry with myself in equal measure.

@fcmf  unfortunately these things happen. I'm so sorry to hear about your fish, and I understand that you feel awful. It was an accident. I know that doesn't make you feel any better, but it could have happened to any of us.

I had a glowlight tetra that got trapped behind the filter bracket, I thought I'd somehow trapped him in there when I'd moved the filter to clean it except the daft thing got itself stuck there the next day, after that I plugged the gap with filter wool. Things like that happen unfortunately don't beat yourself up too much.

Your female could be full of eggs fcmf, maybe a water change with cooler water will trigger a spawning.

Thanks, both.

I decided that everyone could do with a treat (the fish) / cheering up (me), so went back to the LFS and bought some frozen food. This seems to have gone down well in the tank. Hoping, in addition to a further water change topped up with cold water, it might induce the huge female to spawn if indeed she's full of eggs - certainly, I see lots of mating behaviour daily but have never yet seen any eggs released (although appreciate they may get gobbled up quickly).