I didn't count the minnows...with that many, c leed's right.
If it's just the minnows and lots of water changes every week, it may be doable...just a lot of work. Is it possible to upgrade to a 55 or a 75 gallon? That would give your comet (just the one) room, and give you room for a larger school of minnows (and more plants! *lol*
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All the plants I listed are low light plants--it if was a light that came with a hood, it'll be fine. If not, give us the wattage and we'll tell you if it'll work. You'd be best served keeping the light on for at least 8 hrs a day unless the tank gets a lot of natural sunlight (but then you'd be fighting algae...tank light's simpler
). Absolutangel's right about the timer. You can get one pretty cheap if your light plug has two prongs--I got mine from Walgreens for 5 bucks. To get a 3 prong, I had to get it from Petsmart, but it was still only, like, 10 bucks.
Your gravel will be fine for them. Anubias, java fern, and floating plants don't need substrate anyway, and the sword plants will grow just fine--a root tab every 3 or 4 months would help it grow, but not strictly necessary. They can be kept in a ten gallon--just trim the leaves off that get too tall. Water Wisteria would also be an option--again, just keep it trimmed down to the height you want. Their preferred temperatures are pretty broad, so no worries on that--the only issues you might have is if you keep it above 85 or so, and you need to be not doing that anyway because of the fish.