Help needed urgently. I'm a beginner with tropical freshwater fish and have been doing reasonably well so far but have a big problem all of a sudden. My 1st Catfish was doing really well and when we looked in the tank last night he was dead. Today my other little Catfish has done the same and my Sailfin Molly (who is greedy but never had an issue) has bloated up. We did have to put our fry into the big tank urgently the other day as our breed tank had leaked? The fry were about 6 weeks old and we're a decent size however some have disappeared? We had put this down to our Silver Dollars as I had seen one devour a fry, I'm assuming mistaking it for food as they are vegetarian? Do I sound like a complete idiot? I'm very worried for my Molly now. Can anyone advise?