Five white clouds in a 3.5 gal?

If they are fullgrown at 1.5" (4cm), that's already too many fish for that size tank.

First off I would not worry about the 5 White Clouds.
And congrats on this great pic for a fish. These are really nice fish and can even reproduce if the conditions are right.
Your aerator sounds good by providing a good current for the fish. Got a filter tied to it??
I would get rid of the pink rocks and the plastic plants.
What you may want to do is to aquascape your small tank.
I think you could make a great little tank of live plants with a piece of driftwood or even some medium sized rocks
to give it some interest so that the focus of the tank is not just the fish but the fish swimming in a cool looking environment.
Do not add any snails at all. They will eat plants and fish eggs.
Here is a cool link to a YouTube on a White Cloud Tank
Plus there are other videos that include Hillstream loaches with the White Clouds.
White Cloud Tank

Here is a link that might be useful: About aquascaping

by aerator i guess you're talking about what i refered to as the "pump" which is a filter. you'll have to excuse me, i'm still very much a novice.

i've been thinking of incorporating some rock/interesting other things in my tank for a bit, so some good suggestions. btw my the pink rocks and green "plants" look fantastic (i really love the way they clash colour-wise together), but i can scale them back and add in some interesting other features. when i set up mu tank i was a bit scared of killing live plants, so i figured i would start with some nice fake ones until i knew i wouldn't kill the fish.

but is there still the possibility of more fish? or do i only have the option of getting a bigger tank before getting more fish?

There is a possibility that you could double your number of fish but it really depends upon the carrying capacity of the tank. With good agitation and a strong current that can help maintain a high rate of oxygen exchange with the surface of the tank then maybe. Also keep in mind that the higher the temperature of the tank the less the carrying capacity would be because warmer water loses oxygen much faster than colder water. That is one reason that fish in the ocean are mre abundant towards either pole though in the tropic there is a greater diversity which I think may be due to microniches.
So if you can keep the temperatures of your tank from the 50sF into the 60sF then you stand a good chance of being able to successfully keep more.

Here is a link that might be useful: Oxygen content in water

What about adding one Corydora catfish? I think they are very entertaining in their own right. They clean the tank. If the white clouds did lay eggs, the cory would not harm them. If you keep the pink rock, make sure it has no sharp edges. You could go for live (green) plants and still maintain your color scheme. (I like the spotted [leopard] corys, but the albinos look pink to me; giving your rock some company.)
I think white cloud mountain fish are super. Go to your public library and find Tan's Fish in the kid's section. Great true story!