So the past years I've been a solid fish killer. But a totally unintentional one. Recently, 3 weeks ago I bought two healthy looking nymph goldfish, I prepared the water for 24 hours with water conditioner and drops before introducing the bag of fish into the water, leaving it for 15 minutes, adding some water to the bag, another 15, then letting the fish swim out into the tank.

NB: I had one plastic plant and some white pebbles that were thoroughly cleaned before being out in the tank, the tank is also the right size for two small goldfish.

So I gave them some fish food (only a little to settle them) and so far so good. This "goodness" continued for two days when in the morning I went to uni after feeding my fish (2 small amounts a day they're fed) and came home that evening to find Pequeño Naranja belly up I'm the tank. I took him out and flushed the poor fella and checked the pH. It was perfectly fine. I changed 1/3 of the water one week after (as to clean up the tank as per fish keeping instructions) and Blanco Jörge was fine, one week went by, changed the water and then two, and today I come home from an overnight stay at my friends - I had fed him the previous morning, and he had passed away and sunk to the bottom, I checked the pH level and it's was again, fine. I did notice on Friday last week, (a week ago) that my little fishle wasn't using(opening) one of his gills, it didn't seem to be struggling and I couldn't find any info on why this would be happening. So yeah I got home and he was at the bottom of the tank, I had a look at his gills and there didn't seem to be any obstructions, but then again I'm not too up to date on the anatomy of a fish.