Hey all, I've got a 38g 4ft long tank with 2 dwarf gouramis, 5 harlequin rasboras, 6 black phantom tetras, 8 cardinal tetras and 6 sterbai corys, about 2 weeks ago I woke up to a dead black phantom which had no eyes left? Now today I woke up and found one of my rasboras dead with the same, no eyes. Any ideas on what could be causing this?? Im happy with my tank and don't want to lose any more fish.