Upside Down Guppy

[wally6346]

i have one male guppy in a tank with some fry in a breeding net (i had two female guppies in there until last night when they died ). the tank is 18"x12"x12" and the fry are 3 days old, i have about 15....just in the last hour he has gone slow and keeps hanging upside down in the corner near some plants....he is the most beautiful guppy and i have had him for a while now and he's always so lively and strong, i dont want to see him go, is there anything i can do...i did a water change this morning after the females died from some sort of fungus....i wish i could have seperated them, i feel really bad, but i had nowhere else as my main tank has fin nippers...
any help is wanted and appreciated!!
thanks

 

[wally6346]

its looking now as if it just can't swim straight, its upside down, twisting all over the place...there are no obvious symtoms, just horrible to watch my favourite fish like this....

 

[wally6346]

its just passed away
i don't get why it happened so suddenly, i'd say in the space of an hour and a half...there were no symtoms, it had eaten fine etc.

if anyone could help to explain this it would be great...i know i've probably mate some terrible beginner mistake but i'm a little confused why it happened like this?

 

[WILDER]

Need to look at your water stats in ammonia,nitrite,nitrate,and ph.
Where was the fungus on the fish and was it fluffy looking.