I'm new to keeping fish but i've had turtles for a long time. I started getting into fish and i put fish into my tank with my turtle. Yesterday my pleco died with no signs of bite marks or anything. it had white splotches on it's skin, just coloration not a parasite and why did it die? its in a 50 gallon temp is 76-78 F ph is 7.5 nitrites is .3mg/ amonia 0 mg/l and nitrate 20mg/lany ideas why it died? its a bushy nose pleco and the tank has a fluval 306 filter and a cascade 600 internal and the tank has been running for about 6 months but fish were introduced two days ago