Retired Geezer here. My neighbor brought over a 2.5 gal tank with one sad guppy for me to watch while he is on vacation.
My wife and I have had tanks before and this triggered happy memories. Well you can guess what happened, we're off to look for a 20-29 gallon tank for ourselves. It's been 40 years since we had fish and I remember the filter was called an 'under gravel filter'. Do they even have these anymore?
Second question. Should lights be on 24/7 or should I turn them off during dark hours to help the fish maintain diurnal rhythm.