Very Very Fat Zebra Danio !!

Hi all,

Im wondering if anyone can help me to identify what might be up with my hugely fat Zebra Danio ?
My tank is 125 litre, fishless cycled 6 months ago, added 5 zebras 2 months ago and after about 3 weeks one of them became noticeably fatter than the others. All ammonia, nitrite, ph tests are fine.
He has no other obvious health issues, eats, swims and chases along with the others etc and seems quite happy. My daughter has called him Johnny Vagas 
Has anyone any idea whats going on with Johnny? and what if anything needs to be done or what the prognosis might be?
I have tried to get a photo but even an obese Danio is fast and hard to photograph 

Hi Sue, the scales are still perfectly flat, they are fed only a small amount, once at 6.30 am when i leave for work and again at 4.30pm when i return, only enough food that its all gone after 2 minutes, its been fat for about 4 or five weeks now, not sure what the gestation period is for an egg laden Danio but i suppose that could be a possibility, will have to change her name from johnny to jenny lol 

Well time will tell i suppose, thank you and i will keep you posted on any developments