Can anyone help diagnose what is killing my fish??
Tank size: 60L
pH: 7.5
ammonia: 0.0
nitrite: 0.0
nitrate: 25-50
kH:
gH:
tank temp: 26
The tank is new (three weeks old) and the ammonia & nitrite levels have been fluctating (ammonia not higher than 0.1, nitrite hit 0.5) although these levels...