Dave's little 11yo sister has started up her own tropical aquarium after we bought her a tank for her birthday, tank was running fine until two unquarrantined Angels were added which caused white spot but after a few doses of Furan 2 everything returned to normal.
She added 4 more small Angels to her tank and 6 tetras - we did a big water change because the water was looking a bit green and stagnant (she does one 50% per week). The smell from vaccuming the gravel smelt of sh*t to be honest (did a 70% waterchange using preheated water).
By evening the following day, 3 healthy Angels had dropped dead + 2 tetras. Wanting to know what could be the possible cause of it, she's at her wits end and crying and wanting to give the fish back to the petshop before anymore dies.
Any suggestions?