I have a 159 litre Marine tank, its now been running for year, Ive had from the Start a blue damsel, and then from then on added 2 clowns, a cleaner wrasse, 1 strawberry gramma, 1 cleaner shrimp, 1 green goby, 1 eibls angel and 1 sunburst butterflyfish, a fairy wrasse and most recently a blennie. I bought the fish around 1 every month, giving the others time to settle in. In the past 3 weeks ive lost The Fairy wrasse, no apparant reason, the i lost the cleaner wrasse, no apperant reason, i then conducted a PH, Ammonia, nitrate n nitrite test, everything is spot on, ive now not seen my blennie for 2 weeks and i woke up this morning a dead clown fish. I did another water test on everything and its all fine, Gravity is 1.024 I cant figure out whats wrong, i was wondering if anyone can help? or if anyone has has similar problems