I have a 38 gallon tank which contained 5 Giant danio's. A week ago, I had discovered a fish dead, with pretty much its stomach exploded and tissue all over the tank, I have no idea how he died, since he was fine the previous day before I shut off the lights, but next morning, not so much. I immediately did a massive water change, probably alittle more then 50% I used my siphon to thoroughly clean the sand of any and all debris and everything seemed fine for the next few days, (so all of this above information might be completely useless, but I will take no chances). Soon after, one of my Danio's started swimming vertically, at the bottom of the tank, with his head facing up. He often stays in the same exact spot and treads the water in this position. However, when it comes to feeding, he has no problem, swimming and fighting with the other danio's for food. Can anyone tell me what is wrong with him?
Video I posted on youtube of my fish swimming vertically, please look at this
---Additional info---
The tank has been running for about 4 months
I do a 25% water change weekly
I dechlorinate the water with Seachem's Prime
The filter is cleaned out monthly, (media rinsed in bucket filled with tank water)
ammonia: 0ppm, nitrite: 0ppm, Nitrates: 20ppm, pH: 7.5
Video I posted on youtube of my fish swimming vertically, please look at this
---Additional info---
The tank has been running for about 4 months
I do a 25% water change weekly
I dechlorinate the water with Seachem's Prime
The filter is cleaned out monthly, (media rinsed in bucket filled with tank water)
ammonia: 0ppm, nitrite: 0ppm, Nitrates: 20ppm, pH: 7.5
