Black Shark Aquarium

I have been keeping fish on and off for decades and decided to start a new tank. All the fish I bought from Black Shark died very quickly. When I mentioned this to the sales person he said something had to be wrong with the quality of the water. I told him exactly what I had been doing and then he just shrugged it off. He was very rude and felt he needed to remind that "they go to the toilet in there" I don't know what the other staff is like but I won't be going back. Waste of time and money!