Tail split? Tail biting? Fin Rot? What's going on with my betta?

[kirbomatic]

I'm not sure what's going on with him, but I think something is wrong. I noticed a split in his caudal fin late last week, and noticed another split today! I also noticed that the tips of that fin seem ragged and receding. I was worried that the split may have been caused by one of the "plants" in his tank so I removed it, but could it possibly be fin rot? What do I do?

Here's what he looked like a couple weeks ago when he built his first bubble nest for me <3

Notice the tail fin's shape.


and here's what he looks like now.



Housing
What size is your tank? 2.5 gallons
What temperature is your tank? 80 F
Does your tank have a filter? No (it came with one but it's too strong)
Does your tank have an air stone or other type of aeration? no
Is your tank heated? Yes
What tank mates does your betta fish live with? n/a

Food
What type of food do you feed your betta fish? Top Fin Color Enhancing Betta Bits x5 daily, Omega One Freeze Dried Blood Worms 1x a week in place of pellets, no food 1 day a week
How often do you feed your betta fish? I feed him two pellets in the morning and three pellets in the evening

Maintenance
How often do you perform a water change? 1x a week
What percentage of the water do you change when you perform a water change? roughly 50%... I change a gallon of the water out of the 2.5, but with the decor in place, it seems closer to 50%.
What type of additives do you add to the water when you perform a water change? 2.5 mL of water conditioner (the bottle says 2.5 mL per gallon and I change a gallon of water), and .5 tsp of Aquarium Salt (the past few water changes because of continuing suspected fin rot)

Water Parameters:
Have you tested your water? If so, what are the following parameters?
not yet, planning another trip to the pet store for the kits asap

Symptoms and Treatment
How has your betta fish's appearance changed? Two splits in caudal (tail) fin about 3/4ths the way to body, edges look more ragged, perhaps a loss of color (i'm also concerned about the darker rust type coloring shown in the picture on his anal fin). He has little tiny black spots on all his fins, but that may be coloring, and his dorsal fin's edges are curled, but have always been, and may have a tiny hole in them..
How has your betta fish's behavior changed? He's as chipper as ever, honestly. He doesn't seemed bothered.
When did you start noticing the symptoms? The first split happened on Thursday I believe, and I just noticed the second split today. I noticed the ragged, receding end of the tail fin on Saturday. I've been worried about fin rot since I got him a month ago, but there didn't seem to be any real symptoms until the split fin.
Have you started treating your fish? If so, how? Not yet other than the aquarium salt.
Does your fish have any history of being ill? Not that I know of. At least not in my possession. The curled tips on the dorsal fin suggest past fin rot to me, from when he was at the store.
How old is your fish (approximately)? I got him a month ago from PetSmart

[kirbomatic]

Aww man he has a split on his anal fin too!
And the weird coloration on his anal fin is actually more of a blood red and it's present on his dorsal fin a little too. Could it just be his coloration or something more sinister? Oh yeah and I have no idea what's going on with his ventral fins. They've always been black like that. Well, lighter on the inside of them, with little black spots. They worry me too.

I just want little Finn the Fish to be okay. Well, more than okay. Splendid. Betta Splendid. Ha. Haha.