So i have noticed that in the recent couple months my goldfish has started hiding alot. It comes out around meal times to eat and swim about a little, then will disappear for a couple hours. It's about 2yrs old now or so and is in a 29gal tank with a tiny CAE that we got 2 weeks ago (I know tank is a tad small and i will be upgrading to a 60gal in a few months but figured the CAE is still small and will be fine for a bit) the water params are 0 ammonia, 0 nitrites, and about 20ish nitrates and i do weekly 25% water changes. The CAE seems to be fine, just swims around sucking on gravel. Just think it's odd because the goldfish used to never hide.