Pregnant or sick?

Question
I know it's a bit difficult without seeing the fish, and also you may not be the right person to ask but no-one else was free so thank you in advance. We are reasonably new to fish keeping. We have a tank that has been going for about three months that we were given complete, with fish, when it had already been going for two years. We added some tetras yesterday, black neons, neons and glowlights. One of the glowlights in particular is very fat. We had a fat black molly before who turned out to be pregnant so I don't want to panic, and as they have only just been moved I don't want to mess about with them unesscessarily but I also don't want it to infect the others. It seems to be the belly that is fat. As far as I can tell the scales aren't sticking out and it is eating and otherwise seems ok. How can I tell if it is a girl? We have started with five so there is a fair chance that they are a mixture of male and female. How long should we leave before it before we worry? I don't want to jump the gun with a treatment in case it affects any eggs that might be layed.The other tetras all seem fine. Thank you very much for your help.

Answer
Hi Ruth,
  Tetras don't get pregnant as such -- they are egg layers.  It could be full of eggs. I would definitely not
treat the fish with anything.  In general, only medicate fish if you know exactly what is wrong with them, otherwise the medicine is often worse than the original problem.

-- Ron
  rcoleman@cichlidresearch.com
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