I tried to click on a chest and instead it got deleted??

I had found koi fish, which I had never seen before and thought were very cute but only had one bucket. So I quickly made a set home and went home to get more iron to make more buckets and to put away the koi fish I had already found. I had two big chest, my top one consisting of important items to me such as ores, other fish I had collected and more. When I went to click on this chest to put my fish away with the octopus it instead just vanished and was replaced with the water and koi fish within my bucket. I quickly “picked up” the fish and water for lack of a better word but that half of the chest was nowhere to be seen, its items included. They had not floated away or gone somewhere and instead vanished. I lost all the ores I had and other important items and I am unable to find them. What do I do?? What happened???