Poorly Guppy

[shev]

Hi there, sorry I can't copy all the info, I'm on my phone.
I've notices this evening One of my guppies has a very thin white string coming from it and looks pregnant. I'm pretty sure he's male though s had a problem with fin rot and lost 6 guppies after our red tailed shark started nipping them at night. Shark has gone now.
Had water tested at lfs and everything ok except nitrates which were sky high.
Tank was bought second hand (125l) with a few platies, 2 loaches, Apple snail, shark, 2 mollies and a sailfin Molly. We kept a third of the water to transport it and topped up with clean water when we got home. I've since found out that most of the filter media was missing and in seriously poor condition.
All this has been sorted now (old media left in for now too) weekly 50% water changes, aquarium salt and myxazin course started.

Sorry for the long post, I just don't want to lose any more fish. Wish I had stayed with just my little 60l tank!

I have pictures but don't know how to add them s

 

[Blitz]

Hi, welcome to the forum.

To tell the difference from a male and female guppy:
Male-Colors should vivid. Bright colors are mostly shown on males. Males a tad bit smaller than females.
Female-Colors a little on the dull side. Females a bit bigger than males.

I'm sorry... but I don't really understand your question.

 

[vigosh]

Firstly, get those sky high nitrates right down. Do smaller daily changes so as to not shock your fish until it is in an acceptable range. Also I would recommend buying a liquid test kit for yourself so you can monitor all your water chemistry at home.
As you have bought your gear second hand including the filter media there might have been something lurking in the tank. I would treat your entire tank with a dewormer. They are readily available and very effective. It may be a case of your fish being constipated, a good cure for this is to feed them some de skinned boiled peas, I would do this first and see if the bloating goes down.