Neon Tetra Acting Strange!! SOLVED.

Are there any other symptoms, for example, you say her belly is bulging but do the scales also stick out?

There are 3 causes for female fish to have bulging bellies - dropsy (the sicking out scales), eating too much at one go or egg bound. If her scales are not sticking out and you hadn't fed the tank within the previous couple of hours, that leaves just option 3. And I'm not sure what to do about egg bound females other than let nature take its course - either she'll reabsorb the eggs or lay them.

Thanks for your replies Sue and Matt. Things have settled down now and I think she may have eaten a bit too much at tea time! No scales sticking out thankfully. Think I might give them a fasting day tomorrow! Thanks again for your help. 

Thanks Fiona. The peas have worked their magic!! Happy Neon this morning!