Disaster in my 36 gal. tank. I woke up this morning to a dead red cherry near the surface, normally this would not raise any alarms, so I waited until the lights came on in the tank. And to my horror, I noticed at least 20 probably more dead red cherry's and two dead tetras. The other cherry's were near the surface hanging on to what they could. My fish were breathing more than usual. What could have happened? This is a day after my weekly 1/3 tank water change, I did not forget my prime, I did nothing else out of the ordinary.
I am in the process of doing water params, and will post them as soon as I have all of them together.
After doing a 50% water change, the tetras have gone back to their usual space in the tank near the bottom, the dwarf neon rainbowfish are playing, my gourami is digging in the substrate for food again. and the cherry's have gone back to their usual selves as well. This leads me to belive that it was low O2? I am not sure why that would suddenly become a problem since I have not changed any equipment nor have removed any plants.
I have removed as many of the dead shrimp as I could find, and the two fish. I am afraid of what might be coming, how should I move forward now to help prevent a massive ammonia spike? the tank is heavily planted, so getting back to some areas of the tank is near imposable. So far most fish are completely accounted for, and the ones that usually hide I have a rough idea that they are ok. I can see to the back of the tank along the substrate and see no more fish or shrimp laying dead.
I forgot to add, this tank is a low tech tank without CO2 injection