Hi everyone. I have 3 guppys and 1 has developed a rather large stomach so i believe it could be pregnant as there has already been 4 babies born a few month ago so i know theres a female guppy. (didnt notice the pregnancy last time as im just new to owning fish and noticed a little baby swimming near the filter then found the other 3 which i took straight out of the tank). Anyway after spotting the big belly i went on youtube to see preganant guppies and mine looks similar so I have put this fish in a seperate tank as i believe there would have been more babies last time but as i wasnt really expecting any babies some could have been sucked into the filter or eaten. last night this guppy was pooing loads and then i noticed 2 red strings hanging out which dont seem to dislodge when the fish poos. I actually thought it might of been a sign of pregnancy and once the strings dislodeged then the babies would come but iv googled it and people are saying it could be a parasite. also at the minute some of the stones in my main tank have turned green even though i have a filter and bottom feeder fish so could this be causing a problem.

Oh my, Camanallus worms then. Common in these fish.

There is a good med out there for this....Give me some time to locate. I had a bad experience (weeks searching) with tank having round worm/nematode problems....

so could the swelling in my fish be from the worms and not actually be pregnant?

Worms yes, pregnant possibly.

This is a nasty little parasite but readily treated by dosing with Levamisole. An effective drug sometimes marketed under the name of 'Chanaverm'.

This site certainly sells it if you have issues sourcing and I have used them before. Good customer service

http://www.fish-treatment.co.uk/roundworms.html

that site gives a good deal of info too on the critters that you should find helpful.