Hello everyone! I am new to FishLore today :;hi1 (yay) and I thought I would ask a question. Before I start: I have a 38 gallon tank with an Angelfish (not aggressive AT ALL), an African Spotted Leaf Fish, four tetras. At the time of the death, I was using an algae liquid to help get rid of some of the algae. So, I went to the store yesterday and bought two Red-Tail Sharks. I know, I know. People all over the internet strongly suggest to only get one because if you have more tan one, one of them will become dominant, but the employee who was helping me strongly suggested I get two. Anyway, I put them in the tank and they were fine for a couple of hours (I acclimated them and did everyone perfectly) but they both died during the night. I was able to return them (well actually the store gave me two new ones instead- and the new ones are doing fine) and I had my tank water tested and everything was perfect- no irregularities. So..... does anyone happen to know what might have happened? Thanks so much guys!