Ummm. Lemme see if I have your tank population straight.
Zebra and leopard danios.
2 “Chinese algae eaters”, I’m assuming you mean “otocinclus”, those teeny little cigar-shaped ones?
Okay, these are all top-water swimmers and top-water feeders (except for the otocinclus). If you’re feeding them granules, you’re feeding them the wrong kind of food. They need flakes that will stay on top and swirl around so everybody can get some. The angelfish will take food in mid-water, but since they’re always gonna be first at the table when the food hits the water, you might as well go with what everybody else needs.
Granules are just wasting your money and making the tank turn green, as you already discovered. It’s the uneaten rotting food crumbs that fall into the gravel and hide under the decorations that’s making the algae grow.
In my experience, the Number One tool for feeding top-water swimmers the correct amount is a feeding ring. You can spend 3 bucks on a fancy injection-molded plastic one in your choice of decorator colors, or you can get a styrofoam coffee cup and a steak knife and carefully saw off the top reinforcing ring of the cup (that thicker part right at the top), being careful not to crack it. You want a perfect styrofoam circle, not a letter “C”. Then you float this in one corner of the tank and always deposit the (tiny) pinch of flakes right there. In three days, tops, you will see that your fish have figured out (a) where the food is and (b) they will have established a hierarchy of who gets to eat first (the angelfish, then the swordtails, then everybody else, I’m betting). This makes it much easier for you to tell how long it’s taking them to clean up the food you give them. If you just drop the flakes in the tank, they go all over the place and you can’t see who’s actually eating and who’s still waiting their turn.
Is this your first fish tank? Do a search here in GQ on “tropical”.
Be aware of the fact that in another month, your angelfish are going to eat your zebra danios. It’s just the way it goes. Also, if your swordtails do manage to produce young, the angelfish will eat them, too. I’m guessing that your angelfish ate your neon tetras. They’re notorious for that. Sorry.
Oh, and they didn’t exactly “clean up the algae themselves”. The otocinclus of course ate a lot of it, but the classic Number One Algae Control solution is simply to stop feeding for a few days.
You don’t need to feed them twice a day. Once a day is fine. Don’t worry about starving them, they really only need tiny amounts of food. What Delta said was good–visualize one flake of food the size of its eye for each fish, and then put exactly that number of flakes into the feeding ring. And don’t worry about mixing and matching the red flakes and the white flakes and the light green flakes and the dark green flakes, 'cause it’s all the same stuff, with food coloring added so it looks nice for you. The fish don’t care.
More advice: I would strongly urge you to either skip the live plants altogether, or at least wait until you know a little more about fish and have your tank well-stabilized before you add live plants. In my experience the rotting plant parts which they shed throws the tank balance out of whack, not to mention clogging up the filter constantly. (You didn’t say what kind of filtration you have.) The worst is elodea, which is the big juicy 9 to 12-inch long dark green leaves, sold in bundles, usually with ramshorn snails attached. :rolleyes: It sheds big juicy dark green leaves constantly and is incredibly messy.
The other plants, the serious aquarist plants, the ones you have to plant in the gravel and fool around with, IMO are just too much trouble. For one thing, there usually isn’t enough light from the average aquarium lighting fixture to make them grow the way they’re supposed to, so they just sit there and die. There goes your fifteen bucks. Or else you go out and buy one of those fancy high-power lighting fixtures, and then you go crazy fiddling with it, trying to get everything balanced and working right.
If you ever find yourself being tempted to buy a Carbon Dioxide injection unit for your fish tank plants, come talk to us again–we have doctors who can help you.
And congratulations for actually understocking your tank! Such self-discipline is rare in one so young…