Nice tank! Good aquascaping. Nice balance and proportion. Dratted turtle is what started me on my long slide to chronic multiple tank syndrome (and sciatica from water changes - Oye ve! - but I digress).
Water treatment: I use Kordon Amquel+ and NovAqua+ together, 5 mls of each per to 7 gallons of water (that's excessive, 2x recommended, but they really do a number on the water at the water authority hereabouts, so better safe). I have seen a lot of people recommend Seachem Prime as a water treatment. The problem is that a lot of water companies add chloramine to the water, and lots of water sources are chock full of heavy metals, nitrates, and unwholesome organic beasties of all shapes and flavors. Now you can get ride of Chlorine just bay aging the water for 24 hours, but Chloramine sticks like a bad habit, so you'll need to juice the water with something to get rid of it (oh, and you water company can add it or change the mix without warning you, so act like they use a ton of it all the time). Read the bottles - if they take care of Chloramine, you'll be fine 99% of the time. If they get rid of heavy metals and dissolved organics too, you can kick that up to 100%.
Fish: A 10 gallon tank is limited in the number and type of fish you can have in it. On the other hand, there are still a metric buttload of different fish you can have. What you are looking for is fish no more than 3" long (no more than 2" unless they're air breathers - like anabantids or cories, or really long and skinny: kuhli loaches), that are not super active (Zebra Danios are right out, for instance - they really need at least 24" of swimming room.)
If you stick with that, then you can use the 1" per gallon rule no worries. You can even bend it to 2" per gallon for small schooling fish (neons or smaller).
With that set up, which is pretty open and light, I'd lower the temperature to 72ºF and get a school of 10 white clouds and a trio of Panda Cories. (I hear the howling in the background, but planetcatfish and scotcat both agree that 72 is in their temp range.) With the snail, that should max out your tank.