I have had my retics stingray for about 4 weeks when I brought him home there was a little white stuff on the tip of his tail, then it went away, I have now noticed his tail is significantly shorter thAn it was to begin with. Some days the tip is white some days it looks normal in color His tank mates are 2 brisel nose plecos there 5 fry( very smAll) 4 silver dollars, a silver tiped black fin shark, a bkg ( 4 inches) an Angelicus Botia Loach I have never saw any of these fish picking on the ray. Could this be some type of fungus or which fish do you think would be responsible

