Hmmm.... Welcome to the forum. Well, I believe that it's normal. Betta's do not like water changes because they live in little dirty puddles in rice fields, so their used to being dirty.
Bettas live in rice paddies (which are actually massive). The water is murky (from tannins and mud), however the water chemistry is perfect. As the OP said, you cannot compare an entire ecosystem with dark water to a a glass tank of much smaller proportions.
Not doing water changes in a Betta's tank means:
the ammonia and nitrates will become very high, poisoning the fish.
This also means you betta will be much more susceptible to disease, and he could even die.
Sure, if you added tannins to your Bettas water he would be much more happy, however this is different to never doing water changes. Unless this all a big misunderstanding and if so, sorry.
The white-ish to clear coloring on the tips of their fins means new fin growth, not fin rot.
Ammonia build up you will see red streaks on his gills and head, along with gasping for air at the surface.. so doesn't sound like ammonia build up.
In a 3 gal filtered, 1 50% water only, and 1 50% substrate only water change per week is recommended. Either vacuume the substrate or mix it up in the tank and dip it out with a cup to get as much of the gook out as you can.
Clamped fins: holding his fins real close to his body and/or squeezing them tight like a folded umbrella.
I would stop the AQ salt, since it is not for a treatment at this time, it is doing more harm then good. You added in salt without the proper 100% daily water changes, which can harm because of the build up. Plus over time it will cause him to become immune to the beneficial properties of it so then it will become void when you actually need it.
You said yesterday you did his first water change, 10%, and when you listed water changes (in order) you done 2 more since yesterday? Did you add in the full amount of the conditioner per water change, and not the reduced amount to match the % of water that was changed?
Are there the appropriate heavy plants (real or fake) and hiding places for him? He may have found a place he feels safe at behind the heater, which some do. He is still new to the tank, so he could be still getting used to it and haven't explored yet.
Also, did you baffle your filter? If you had not, that could easily be why he stays in the corners because the current is too strong for him and stressing him out. A lot of bettas do not like, and do not do good with filters. Don't stop and start your filter, either keep it off and up the water change to 1 50% and 1 100% per week, or baffle it.
It doesn't sound as if he is sick, but more like he is stressed.
I meant that it's likely the ammonia built up as well as nitrates and such from the water not being changed enough. Red streaks along fins and such show up when there is extreme ammonia poisoning, the fish can still be suffering from lack of water changes without having horrible ammonia burns.
You are correct GreenTea, there can most definitely be ammonia/nitrate/ite poisoning without the burns. I should have been more specific and say in my opinion it doesn't sound like it to me. My apologies.
Okay, so his behavior has improved, but I think his tail is getting worse. Here is a picture of him. I have some more, but none are as good quality as that one. Does this look like fin rot? or am I just being super paranoid?
There seems to be some black/frayed edging to it, as well as new growth. But it's not too bad. Glad to hear he is acting better though.
Now that there is a pic, I can be comfortable saying to go ahead and treat for fin rot. He may not have it, but it looks like it could be the start. So as a preventative I would recommend doing the treatment. *Unless his tail fin has always had black/dark spots on it. But if it is new then proceed with treatment.*
1 teaspoon of aquarium salt per gallon. Dissolve the salt prior to adding it in the tank. Make sure to add in the correct amount of water conditioner as well. Do daily 100% water changes to avoid salt build up and to keep the water as clean as possible. Do the treatment for 10 days. If you don't see much improvement then up it to 14 days.
If you have Stress Coat+, you can use that instead of the water conditioner to promote fin growth. You can also use it after treatment.
The ammonia is a little high, if you start the fin rot treatment then the water change will lower it. If you can't start it soon, then do a 50-75% water change asap to lower it. You want it at 0, no more then .25ppm.
After that I would do what I recommended before filtered- 2 50% changes per week with full dose of conditioner. 1 water only, 1 substrate. Or 1 50% water only and 1 100% water change. Unfiltered 1 50% and 1 100% per week change.
Thanks so much for your advice Myates!! I've been doing the fin rot treatment you suggested, but I'm not sure if it's working. The whitish part of his tail has seemed to get larger, and the ends are looking even more frayed. I know you had said that the white could just be fin growth, but I can't really tell if it is growth or further rot. If this is more rot, is there anything more I can do for treatment? Here are a bunch of pictures of him. It was tough to get a good picture of him because he has recently taken to swimming quickly back and forth across the front of the tank.
You are most welcome.
His fins actually look pretty good. Finish the 10 day treatment, if you are worried you can up the salt to 2tsp/gal with the 100% daily water changes along with conditioner. Once the 10 days is up keep up with his weekly water changes and he should be fine. Stress Coat (you can get in pets stores and Walmart) will help promote fin growth, so you can add that in as well.
Their fins are like tissue paper, so it's easy to fray/split them. From decorations, to substrate, filters, flaring and swimming fast can do it as well. Since he is still new then he is gaining more strength and everything will get a little tougher, as well as with a balanced diet he is now receiving since you got him. Keep an eye for black edging, as well as make sure he isn't biting his own tail. They do that at times when they are either stressed/bored/heavy tail and not used to swimming. You will notice half circles missing from the edges of his fins.
But in all honesty, once his 10 days is up he shouldn't have fin rot anymore. But always good to keep an eye. If he happens to get it again soon, or the black comes back we can try an anti-fungus medicine. But this conservative treatment you are doing usually does the trick.
Keep us updated on your handsome guy!