Hello,
I have recently set up a five-gallon aquarium with 5 guppies (2 males + 3 females). It has only been 13 days since adding the fish and 2 females and 1 male have died. I thought the first female death was due to stress from being picked on by the other fish because she was quite a bit smaller and the largest female was quite aggressive. The largest female died next, with almost no apparent symptoms leading up to the death. On the day that she died, she was struggling to swim correctly and was mostly on the bottom. I thought maybe it was due to constipation/a swim bladder issue, but she died very quickly. I did notice when I took her out of the tank that her vent was swollen and reddish, not sure what that could mean. Today, I had one of the males also experience difficulty swimming. I separated him from the tank and he died shortly after. There were no apparent symptoms yesterday. Also, the fish sometimes have black/dark eyes. I looked this up, and it said it could be due to stress or the fish showing aggression so not sure about that either. Lastly, with less fish in the tank; the male guppies have been picking on each other's tails more. Could it be a bacterial infection that killed him?
Water parameters:
Ammonia: 0 ppm
Nitrite: 0 ppm
Nitrate: 0 ppm
pH: 6.8-7.2
GH: 150-300 ppm
KH: 40 ppm
Temp: 71-72
Jacob