I recently purchased a small tank (5 gallon) and 2 fancy goldfish for my grandsons first pets. He lives with us and is 3 years old. I am very watchful to be sure he puts nothing in the tank unless I’m there to help him feed them twice a day. The water gets a 50% change out with spring water once a week and an entire tank clean once a month. Then after always goes cloudy. I purchased a bio stone and followed the instructions. I test the water, the levels for everything read they are good except the ph is occasionally in the high end of ok so I use some ph down. The temperature of the tank hangs between 76 and 78 the tank does not have a heater. The filter came with the tank kit so I’m assuming it is the correct size. The fish seem to spend a lot of time at the top although they do sleep/rest at the bottom and don’t seem to have trouble going down to forage and things like that so I don’t think swim bladder. Since my first though was oxygen I bought a bubbler in case the filter wasn’t oxygenating the water enough, but they are still exhibiting this behavior Even after the addition of the bubbler. Do I need to worry? Is there something I’ve overlooked?