Help my fish died
i bought a new fish tank and several fish everything has gone well until today. Ive had the tank for about 2-3 weeks. I acidently dumped to much bottom feeder food in the tank. So Sat. we completely changed the water and washed off the rocks and all the plants. Today both my black fin sharks were dead and one of my speckeld catfish please give me a idea of what to do. I need my black fin sharks but i don't want to go get anymore until i find out what happened