Reddish Patches Showing Up On Betta

I've noticed this in both of my fish before I even get started and I don't know whether it's because they're both white fish or what, but there's something going on.

Both of my Betta were white when I bought them. The first one, Yukine, I've had since Valentine's Day of this year, and the second, Niji, I got two weeks ago.

When I first received Yukine, he was mostly white, save for a few black places outlining his scales. He's been sick from the start, but he's been doing pretty well for a while (besides me treating him for fin biting). Ever since I got him, he's been slowly growing more black, but his body has turned from white to a more, reddish tint. It's not exactly red, but more orange looking... His fins are also have black streaks in them, but that's been normal for a while.

Niji is a white fish except when he moves; then you can see tints of a pale pink, green, and blue. He too is slowly getting an orange looking spot just above one of his eyes and it stretches over to the other.

Niji has different circumstances than Yukine because Niji lived in a 1 gallon tank until a few days ago when I bought him a 1.5 identical to Yukine's. Niji's orange spot has really because more noticeable to me until now, but I'm sure that it wasn't there when I bought him.

Housing:
How many gallons is your tank? Both: 1.5
Does it have a filter? Both: Yes
Does it have a heater? Both: No.
What temperature is your tank?
Yukine: 77°F
Niji: Unknown
Does your tank have an air stone or other type of aeration? Both: No.
Does your Betta have tank mates? What kind?
Yukine: One horned nerite snail.
Niji: None.

Food:
What food brand do you use? Both: TetraMin tropical flakes; occasionally Aqua Culture Betta pellet food
Do you feed flakes or pellets? Both. Niji gets pellets more though.
How often do you feed your Betta? How much? One a day, a small pinch of flakes or four to five pellets; it all depends on what I give them.

Maintenance:
Before your Betta became ill how often did you perform a water change? They both get water changes every other day.
What percentage of water did you change? 25%
Do you vacuum the substrate or just dip out water? With water changes I only dip out the water, but I have a vacuum.
What additives do you use? API Aquarium salt, API Stress Coat (2-3ml), API Betta water conditioner.

Symptoms and Treatment:

When did you first notice the symptoms?
Yukine: A couple of months.
Niji: Last week
How has your Betta’s appearance changed?
Their white color is slowly fading to a more orange tint.
How has your Betta’s behavior changed?
Nothing that I've noticed out of the two of them. I don't know if this is strange, but Niji plays with the rocks (he didn't do this in his previous tank and I've changed gravel since then).
Is your Betta still eating?
Both: Yes.
Have you started treating your Betta? If so, how?
I don't really know how to treat them.
Does your Betta have any history of being ill?
Yukine has had ick and is currently fin biting.
How long have you owned your Betta? Was he or she ill or suffering some sort of damage when purchased?
I've had Yukine since February 13, 2016; he was missing his back fin and had ick soon after I got him. I purchased Niji on May 28, 2016 and he was fin in the store.

I've searched a lot of places to figure out why they're getting this type of coloration to their scales, but I can't find anything. Am I just imagining this whole thing or is there something wrong with my fish?

Thank you in advance.