I have done everything by the book - oxygenating plant, dechlorinated water,test kit, proper food, no overfeeding, occasional pea for them to nibble. They seem to last about 3 weeks and then get a fungal infection. I treated this one with Gold - disease safe, straight away, isolated it etc.
This is the second one that has died. I must be doing something wrong, but I can't think what. I have an electric filter, and prepared the tank 2 weeks before putting the fish in, as instructed by man in shop.
Nitrite levels have always been fine. The only thing is I think my water is a bit hard - could that be enough to kill the fish?
Sorry this is so long. I would be grateful for any advice. Dd (8) is going to be so upset. Maybe I should have let her have a hamster?