1addam

Hi forum, I have a problem with my electric yellows, they have all been under three yrs old,I have a 340l tank with 18 malawi cichlids,and two bristlenose catfish I have lost 3 yellows in the last month, they start off by swimming in a corkscrew motion or head over tail, when this starts off they last for about 3 to 4 days, I have tested the water quality and it is within the suggested limits, I clean the tank every two weeks and the temp is around 26, apart from a couple of the bigger fish fighting with each other, the only thing that seems different is that all the fish don't seem to be eating their food as quickly, I have tried changing the brand to see if it makes a difference,but it doesn't, I have been adding melafix to the water for the last four days ,5ml to every 40l,I would appreciate any suggestions why this is happening or a cure, best regards Addam.