Is this Fin Rot or Tail Biting?

[Connieconcon]

Housing
What size is your tank? 2.5 Gallons
What temperature is your tank? 80~82
Does your tank have a filter? Yes
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? None

Food
What type of food do you feed your betta fish? Hikari Pellets
How often do you feed your betta fish? 3 pellets in the morning, fasting once a week.

Maintenance
How often do you perform a water change? 100% every 3-4 days
What type of additives do you add to the water when you perform a water change? Stress Coat, Water conditioner/declorinator

Water Parameters:
Have you tested your water? If so, what are the following parameters?
Ammonia:0
Nitrite:0.05
Nitrate:0
pH: 7.6
Hardness: I have hard water, but I don't know how hard.
Alkalinity: "Normal"

Symptoms and Treatment
How has your betta fish's appearance changed? (see pictures. Sorry about the picture size. I cropped it in Photobucket, but for some reason they're still showing up huge.)
How has your betta fish's behavior changed? Very little. He's still very active. He chases his reflection and eats enthusiastically. He won't eat Blood worms though. :( He did stop blowing bubble nests.
When did you start noticing the symptoms? From Day One.
Have you started treating your fish? If so, how? First I tried AQ salt, then I tried AQ salt + betta revive, then I tried Melafix.

He doesn't have any of the fuzzy growth I've seen with fin rot in the past. I'm not sure what meds to try now. :(

This is Tweak today.




This was Tweak a month ago.


This was Tweak when I first got him.

[Rain Drop]

It could be a bacterial fin rot, but I'm not 100% sure....

[Colibri]

It might be tail-biting. I can't distinguish the usual markings at the end of the tail when it's fin rot. Is his tank decorated? Maybe he's bored or there's something stressing him. Does he chase his reflection because you show him a mirror, or can he see it in the glass of his tank?

[Connieconcon]

I didn't see any of the fungal growth that comes with fin rot on him either. Do you think maybe I should try some antibiotics or something?

He's got two plants and a floating betta log. He's got two other plants that are not in the tank right now that I rotate in when I change the water. I try to get him to flare at his reflection for a little bit every day by holding up a mirror but he seems more amused by his reflection in the tank walls.

[Colibri]

If you can't distinguish either the fin rot, no antibiotic is really the best. It's never a good thing treat for something that's not even there. You could try some aquarium salt to prevent any infection on the bites. Biting is often related to stress or boredom. Perhaps the fact he can see his reflection on the tank glass makes him nervous because his "rival" whatever he does won't go away.

[Connieconcon]

Yeah, I'm going to try to cover up the sides of the tank and see if he calms down.

[Colibri]

That should do it. Also, try placing new objects near his tank. Bettas are very curious fish, so placing new things will keep him occupied and won't give him the chance to see his reflection.

[Connieconcon]

I'm gonna give him a new plant tonight. :D Do you think maybe the water changes are stressing him out and causing him to tail bite?

I use the cup he came in to scoop him out when I change the water, but maybe I should used clouded tupperware since he flips out in his cup.

[Colibri]

If you're doing 100% water changes every other day... I do think that could be stressing him. If you have a filter... you could do a 50% water change every 3-4 days. Depending on the type of filter you're using, it would be a good idea to siphon the bottom. I do 50% water changes every 4 days and siphon the gravel at the bottom. That way, I do a 100% water change every 2 weeks more or less. All my bettas live in 2.5 gallons and are healhy and happy little ones.

[Connieconcon]

i've been doing 100% changes every 3-4 days. I should get a siphon and try your schedule then.