fish dying

[flora]

hi i am new to this foram and hope you can help i have a 5ft by 2ft6inch tank [aprox] wich was given to me a year ago everything has been fine my freind set the tank up and the fish he sent with lasted well the problem i have is that over the last week i have bought some new fish oh sorry the fish i have already are guppies who are breeding like mad xray tetras red eye tetras a couple of female swordtails two flying foxes some algea eaters and a catfish i did have some neons but these died so here the prblem starts i bought two angel kio and both have died within a week from appearing to be healthy now i have got 6 new neans yesterday and two have been eaten the the swordtails and the red eye tetras were going mad over the bodies of these neons can fish suddenly turn into canabals? i have done ahalf waterchange recently and all the old fish are fine please caan you help as i would like to add some new but am now worried they might die too

 

[Tokis-Phoenix]

Hi and welcome to the forum
When was the last time you tested your water quality for ammonia/nitrates/nitrites and do you have the results handy? Can you descraibe any symtoms or odd behavior the fish were showing before they died like rapid gill movement/breathing or hanging around near the surface/bottom of the tank lots or the fish flicking and rubbing themsleves on objects in the tank etc?