Ok my friend decided to set up a golf fish tank. After gettin her mums smaller tank (mum went big) she set it up, cycled it, and then got the fish. 3 little gold fish. All 3 died within 8 days. Only one showed a sign of kinda changin to a blochy black colour. Ok 3 weeks gone by, 7 fish in total have died. (brought 7 in total) The last one to die also showed the blochy black colour. Only other thing that they show is sittin at the top of the tank.
Please any ideas on what is wrong with her tank??? Everything she puts in there dies.