ok,my cichlids have been dieing one by one for about 3 weeks..One every 2-3 days...I havent done anything different to tank,no chemicals ect..I do 1/3 water changes weekly.We have well water.Water from tap tests ok...Water is crystal clear.. I will start with parrameters ,amonia 0,nitrites 0, nitrates 35,ph 7.5...Tank is a 180 gallon with a 55 gallon wet dry.I have approx 26 ,3 inch cichlids in tank with one 4.5 inc yellow lab..There apears to be no noticible aggression during daylight hours that I have seen.I dont see any signs of disease on fish..I feed flake and sinking pellet in 2 small meals daily..Temp is between 77 and 80 f..Fish are active and appear healthy.I am losing my mind over this.I dont even see them die,I wake up and one is dead overnite...Is the bigger yellow lab scaring the s@#$ out of them at night??They dont have signs of being eaten ,(fins nipped,ect.)when I scoop the carcus out...One thing I have noticed is I dont have to clean the inside glass anymore with my magnetic cleaner thing.Inside glass is always clean and I have no signs of algae at all,I mean nothing...Could this be a problem?No algae,low 02 saturation?Fish dont appear to be tachypnic...I am at wits end and have no ideas.At this rate I should have no fish in about 3 or 4 months.At which time I will sell the tank rather than lose another 300 bucks restocking...HELP!!!!!!!!!!!!