Hi everyone, I am hoping to figure out why my goldfish died in the night. I have had it in a 29 gallon tank for about a year now. The fish was around 2.5 years old. In the past few months I have noticed it laying at the bottom of the tank in the corner basically lounging away. He always ate and acted normal besides this beahvior. People on this forum have often told me this is normal for a goldfish so i kept on with my water changes and thought nothing of it. But this morning he was dead on the bottom and had what looked like a bruise on the belly between the two pectoral fins. I wonder if i missed this bruise sometime in the last few days. I already buried the fish in my garden without any pictures so i cant hekp you there, sorry lol. Anyways, im hoping to identify what mayve caused his death in case it was something i can prevent in the future. I do vigorous water changes in this tank and always check water quality. Ammonia never gets above .25 and thats rare. Nitrite always 0 and nitrates remain under 20. I do 10% daily and 25% every sunday, with a 50% every 4 weeks on sunday. The reason this is so rigorous is because i keep 3 commons in this tank. Before anyone flips out about stocking, these fish were given to me from someone who no longer wqnted them and was keeping them in extremly poor health in college. This was how i started my fish hobby too. I have been trying to find a pond all these years and have been unsucsesful. I digress, if anyone has any ideas as to what went wrong let me know. I think it was a combo of water quality and size of tank, which kind of go hand in hand.