http://forum.aqua-fish.net/ A forum devoted to aquarium fish, plants, techniques and fish keeping as a whole. en http://forum.aqua-fish.net/?topic=saltwater-fish-lifespan#1 I have a problem with marine fish dying - almost all last 6-8 weeks. I say almost because one domino fish has lasted four months. I have tried a succession of red sea chromis, blue damsels, humbugs and clown fish all with the same result. Water indicators appear fine: temp 25 deg C, salt 1.022, pH 8.3, NH3 and NO2 zero, NO3 20, KH 160 ppm. I have two separate tanks, and all fish appear fine until they suddenly die, with remarkable consistency with respect to time. I am buying them from the same source. jagshield 2011-12-05 http://forum.aqua-fish.net/?topic=saltwater-fish-lifespan#2 That sounds as high concentration of nitrates, thus your fish may be suffering from this issue. Definitely there's a problem with the cycling process. jan 2011-12-06 http://forum.aqua-fish.net/?topic=saltwater-fish-lifespan#3 Thanks. I've never had a problem with nitrates at 20 for freshwater fish, but it appears from your comments and further reading that with saltwater the level needs to be even lower. I'll try more regular water changes - from the tap nitrates read 5-10. jagshield 2011-12-06