So I just got a betta fish at Christmas,( actually is was a few days before) anyhow I have a 3.5 gallon tank with a heater, a filter which I placed a cup around so the current wouldn't be to strong, a sideways teacup for her to hide in theand a plant of death. The only problem i can think of is that my Ph is a bit high (7.7) Though I thought this would be a pretty much perfect set up (I did my research) she still doesn't seem happy, or overly healthy( dosen't eat much or swim around alot) And I have just a few question...
A) is there anything obviously wrong with this that I've overlooked?
B) the plant is leaving microspic leaves everywhere and I think it's dying, is there a snail I can get that will eat the tiny leaves? Preferably one that won't get to big cuz they freak me out.
C) Does anyone know of a really good smaller tank for my betta, and a better type of fish for this set up? I'd like a smaller tank, I don't mind the extra work.

I think your PH is a little high, did you test for anything else, ammonia,nitrite,or nitrate? these three are more or just as important. did you cycle the tank? if the plant is dead remove it and try to clean out as much dead material as possible the decaying leaves wont help. theres a general rule for fish size to tank size, it is 1" of fish for every 1 gallon of water, so your 3.5 gallon tank will comfortably house 3.5 inchs of fish. I dont think your betta would be happy in anything much smaller.

also what is the temp of the water?

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90 gallon, 1 Iridescent shark, 2 Pleco, 3 Goldfish, 5 Cory cats, 2 Nerite snails
5 gallon hex, Blue Crowntail Betta, 1 nerite snail,

you can't properly house any other fish in that tank realistically. I know that sounds weird especially coming from someone who housed 2 wcm in a 3 gallon for several months successfully, but regardless of the success I had I wouldn't recommend it. I have found the fish a new home. Bettas are pretty much the only type of fish you can put in a tank smaller than 8ish gallons. You could also try various shrimp in your tank or a mystery snail. I happen to love mystery snails and they are actually quite fun and interesting to watch.

Also your ph is fine. The last time I tested mine I was between 7.6 - 8.0. Most fish (unless they are super sensitive like discus) will adapt to most ph conditions unless it is too high (over 8.8ish) or too low (below 6). Basically I wouldn't worry about it.

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Do I have to take her out to cycle it? And also how do you cycle it, I'm pretty confused. My filter isn't a bio filter I don't think, an would better plants and more gravel help build up the good bacteria?

Do you have a heater in the tank? If so, what temp is it at? Bettas like temps in the 80's, ideally around 84.

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"Being ignorant is not so much a Shame, as being unwilling to learn".-- Benjamin Franklin

To answer your questions I haven't tested for ammonia, nitrate or the like. The temperature stays around a fairly consistent 78 degrees. Will she hurt shrimp? She managed to kill a whole group of terra when she was in my grandma's 8 gallon tank. How big are mystery snails? Also my fish is like 3cm, she's sooo tiny and cute!!! And I took out the plant like reccomended but the tiny leaves are still stuck to everything though I thought I got them out:( what eats this stuff?

Yea the betta will probably kill the shrimp and if it is attacking things I wouldn't put any other fish with it. mystery snails get to be around an inch I would say, idk mine is pretty big.

Here is an image of one of my pond snails on top of my mystery to give you a size comparison.

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Firered, for a very novice fishkeeper you are doing a very good job with your Betta. Keep it up. Here is a bit of info I can share with you. First 78 degrees F is just fine for bettas, i wouldn't go any cooler and you could go a couple degrees warmer if you want. Second, water quality PH can be important but 7.8 is not bad, the key with PH is keeping it constant. If your fish is used to a PH of 7.8 try to keep it at 7.8. Ammonia, nitrate, and nitrite kills fish, get yourself at the least the dip type test strips. If you can afford it get the API "Freshwater Master Kit" which is a reagent based water test system, it is the most accurate and reminds you of chemistry class . With your tank being so young you will have a cycle going on for a while, to prevent new tank syndrome (fish dying from ammonia and nitrate spikes) keep a close eye on your water quality, test at least daily if not 2x a day. Remember you need a little ammonia to start building the bacteria that eat/destroy ammonia. If you ammonia gets over .5 parts per million (ppm) I would recommend a partial water change, at least enough to get the levels down but not to 0. In 4 to 6 weeks your tank should stabilize it self. Speaking of water changes make sure you are using a quality chlorine/chlorimide remover with your water. Those chemicals do not naturally break down, are toxic to fish, and is often found in tap water.

Enjoy your Betta!