Fin Rot, or Tail Biting?

[Korbexo]

Alright so first off,

Housing
What size is your tank? 10 gal
What temperature is your tank? 78 degrees F
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? Pellets
How often do you feed your betta fish? Once or twice a day, 4-5 pellets per day.

Maintenance
How often do you perform a water change? Twice a week.
What percentage of the water do you change when you perform a water change? 50% one day, 50% with gravel vac the other.
What type of additives do you add to the water when you perform a water change? Slime coat +

Water Parameters:
Have you tested your water? If so, what are the following parameters?

Ammonia:
Nitrite:
Nitrate:
pH:
Hardness:
Alkalinity:

Symptoms and Treatment
How has your betta fish's appearance changed? Ragged tail and dorsal fins.
How has your betta fish's behavior changed? None.
When did you start noticing the symptoms? A week ago.
Have you started treating your fish? If so, how? No.
Does your fish have any history of being ill? No.
How old is your fish (approximately)? I got him in October.

I got my betta Arejay while I was at school in October. While there he was in an unfiltered, heated, 2 gallon tank which I did 100% water changes to weekly. While there he had zero issues and was healthy as could be, his fins were beautiful and unmarred.
When I moved back home for break I brought him and put him into the 10 gallon described above. He was doing fantastic, until one day I checked up on him and noticed that his tail was jagged, like big chunks were taken out of it. This was sudden, the night before his fins had been fine. I kept an eye on him, and a few days later the same thing had happened to his dorsal fin.
I don't think it's rot, since it was extremely sudden, but I'm wondering, is he actually biting his tail? He has the same decorations he did in the 2 gallon, the only added thing is a live anubias plant, betta leaf, and moss ball.(None of which I think would injure him.) The other new addition is the filter. I have put aquarium sponge into the intake to cut down on the pull, but is it possible he got sucked in there? I keep checking on him, and his dorsal is healing very nicely, but his tail seems to heal a little, then suddenly go back to the tears and chunks missing. Any input is greatly appreciated, and maybe some tips to help the healing process along? Thanks! Here's a before and after picture

[ChoclateBetta]

I think I see the black edges of fin rot.

[callistra]

It's kind of hard to tell from your photos. They're blurry and dark. Sorry.

You mean Stress Coat conditioner?

It's very common when doing a fish in cycle method for fish to develop a bit of fin rot. While you were doing the cycle you should have been testing daily for ammonia and nitrite. In addition to your weekly water change of around 25-50%, you would have to do more water changes depending on your tests. You would have seen an ammonia spike first and done a water change any time you saw as little as .25ppm ammonia. After that you would start seeing nitrites, and you should have done a change any time you saw as little as .25ppm ammonia or nitrites. After a month or two both ammonia should have gone to 0 and you should have been left with nitrates which would be kept <20ppm by once weekly water change between 50-25%, including the gravel vac.

What are your levels now? When did you put him in the new tank?

The betta hammock has metal in it: the metal must be removed. http://www.amazon.com/Zoo-Med-Betta-.../dp/B0027IZ6KW

If you've got an HOB filter I would suggest using a presponge filter to make sure his long fins or even himself don't get snagged in it: http://www.amazon.com/s/ref=nb_sb_no...efilter+sponge

[Korbexo]

Yes I'm using the stress coat conditioner(Sorry title mix up there). I put him the the tank a little over three weeks ago, but I ran out of the water tester a few days ago so I'm not sure on the current levels. I haven't been able to get more since I've been working everyday, but plan to asap. He's had a black edge to his fins since I've had him. The rips showed up about a week and a half after I added him to the tank and appeared within a period of 8 hours(They were fine before I went to bed, when I woke up they rips and tears were there), does fin rot usually happen that fast?
I believe what I have is an HOB filter, it's a Top Fin power filter 10. Would the presponge filter just wrap around the intake? I'll definitely be getting some for both of my tanks.
I tried to get some better pictures but really only ended up with one(It's really hard to get a clear one since he moves around so much, sorry!)

[callistra]

I think he may be biting. He may be stressed by the cycling. Once it completes hopefully he will stop. I do see some graying to a few of the tips though.. I think there is a bit of rot involved too. Maybe he bit first and now there's a bit of infection.

It's not bad at all and his coloring is quite vibrant. I would just make sure to test your water more often and keep levels as good as possible.. cycling should hopefully be almost complete. If it doesn't get any worse than that I wouldn't worry. If you start seeing a lot more maybe you need to remove him and treat with aquarium salt.. but then your tank will need a source of ammonia to keep it going.

Yep prefilter goes around the intake

[FishFriend9292]

I don't think that I see the edges, I think that is just the colors. Halfmoons tend to tail bite, because of all of their heavy finance.

[callistra]

I pulled it into photoshop. There's graying and a little fraying up towards the top. It's really really mild though

[Korbexo]

Thanks so much for the replies! Very helpful. I'll definitely keep an eye on him(and the water levels! I think I'll be able to hit the store tomorrow for some more testers), and I just bought some prefilters so hopefully they'll be in soon! His dorsal fin has been healing great with lots of new growth, so hopefully his tail will follow suit soon. :)

[ChoclateBetta]

I would boost water changes and add Marimo.

[Silverfang]

That appears to be classic biting. Although there is a chance it could be filter related. You said you covered the intake? I use those fluval pre filter sponges in my shrimp tank. Fair warning, you will need to rinse it out every so often.

Clean water and a high protein diet should help. He might also feel more secure with a few more plants.