hi all, this happened a few weeks back. What happened was I overdosed the CO2 for a too long period. almost half of the cardinal tetras died, while the remaining had white spots on their bodies. each fish had about 6 or 7 small but visible spots on their bodies. i forgot to inspect the dead ones. is this a sign of CO2 poisoning? is it same for other fish or is it just for cardinal tetras. after a few days, the white spots were gone. and the fish were mostly healthy again.