Male guppies with fin issues and one with color

I have two male guppies left from a batch I bought from my nearest pet store. I purchased 9 total a mix of males and females about 1.5 to 2 months ago (5 males, 4 females). I have 2 females left from that purchase who look great and have been doing fine and one had babies. About 2 weeks ago I lost a male guppy who had fin damage, with a large missing bit from the fin. I have 2 males left and they concern me.

The first male has lost a lot of his color and gotten pale or bleached, and I think his tail is getting smaller evenly from all sides starting from the tip. He was a really nice yellow/greenish blue color previously. He is also staying near this area of the tank and not swimming around and exploring as much like the other guppies.



The other male has ragged fins


All my females look great, I have 2 from left from the pet store and I bought 5 more females online from a fish breeder and they are all very healthy looking and active. These are my last 2 males and I don't want to lose either of them.

My tank water tests
ph = about 7.8 or 8
TDS = 338
GH about 7
KH about 3
Temp = 76.9 ( no heater but it stays about 76.8 to 78 degrees)
Ammonia 0
Nitrite 0
Nitrate 5-10 (was about 20 a couple days ago)
phosphate 0 - 0.25 (hard to read color test)
copper 0

I have been feeding Hikari Fancy Guppy, and occasionally some algae wafers to supplement.
I have a heavily planted 30 gal long tank that has been set up for about 2-3 months and ammonia hasn't been an issue for a while. My tap water comes with ammonia so when i started using RO/DI water remineralized it helped with ammonia levels. I haven't changed water in a while as tests have been consistently good. I have a sponge filter and am running a hang on back for mechanical filtration atm. 2 inches of Gravel substrate, some dragon stone, Malaysian driftwood, and cholla wood. There are a few root tabs in the gravel and I dose liquid fertilizer as needed when my tests run low from Nitrate.
There are amano shrimp, cherry shrimp, bladder snails, 4 mystery snails, and a total of 9 guppies with 2 fry that hide in the guppy grass.

Thanks in advance.

Looks like fin rot. Perform 40%+ water changes per day, for a week.

You can also add 1 tsp per gallon of aquarium salt to the water.

What brand of food do you have? Fish can loose color because they are either stressed, or have a poor nutrition source.

I've been using Hikari Fancy Guppy once a day, and some days I add Hikari sinking algae wafers broken up for the guppies, shrimp, and snails to share later in the day. I'll throw in two or three pieces of crab cuisine occasionally for the snails and shrimp, but that's too hard for the guppies to eat usually.