I did some tank maintenance yesterday where I did about a 40% water change and cleaned a fair bit of green and brown algae (as well as a bit of blue-green algae) out of my tank. As per usual, all of my tiger barbs hid while I was doing so. There was one exception that was swimming in a more open part of the tank with its mouth apparently stuck open. I completed my maintenance with no other weird occurrences.
Later that night, I found my some of my barbs gasping for air at the surface and discovered that the solenoid on my CO2
regulator hadn't shut off properly. I turned off the CO2
, re-positioned the filter output to give the tank a fair bit of surface agitation, and left it over night.
Today, the CO2
levels are next to 0 but my barbs all seem off. Some are just lethargic but others are exhibiting more concerning behaviors such as swimming head down, and being uninterested in food. There's also one that is missing. I can't find a body so I'm not sure if it's dead or just hiding.
Does anyone have any ideas what may have happened? I had a similar occurrence a few months ago after tank maintenance (without the CO2
issue) and can't seem to figure out what's triggering my barb's distress.
Ammonia - 0
Nitrite - 0
Nitrate - 10ish
pH - 6.8 (This is higher than usual. It's usually about 6.4)