Your betta was stressed because the filter flow was too strong and he was being tossed around if you had properly baffled the filter he would have been fine! Also he can't swim much in the tiny tank you keep him in so his muscle level is very low :o
I don't think we should make assumptions about other people's fih based on thw behaviors of our own
I think 1 gallons are fine. Each betta is different, I'm running a HOB on my 1 gallon and my fish doesn't mind the flow at all. he grew up with a strong filter flow...and he has pretty heavy finnage.
Honestly, my opinion is..."what ever keeps the fish happy".
My LFS has a plakat in a 110g with other fish. the other fish are all friendly and nin aggressive, but this big Mr plakat is so uncomfortable in the bug space that he stakes out in the top right corner of the tank and hardly ever moves.... perhaps for fear that his territory will be taken if he leaves.
so is a large tank neccessary, probably not at all. some betta only claim territories that is 1 gallon in size... even if he is in a 100gallon tank. In cases like this, I think it's perfectly fine to put them in a 1 gallon tank as long as said tank can be kept clean.
owners tend to know their own fish best. for me, I don't keep a cover on the tank even though the water level is almost at the rim. this is because I've had my fish long enough to know that he will not jump even if his life depended on it...
none of my fish would tolerate a 1 gallon, my HMPK is so full of energy a 5 gallon is too small for him, my female enjoys exploring her 10 gallon and my 2.5 gallon for my VT male is too small for him, he's getting a 5.5 gallon soon.
I have 3 of mine in 1 gals, 1 in a 2.5, and one in the 30. Poor Jade doesn't quite know what to do with the space. Like the plakat mentioned above, she stakes out a corner, until my fiance feeds the fish, then she comes out looking for food.
Aside from that, everyone else is in 2.5 or less. I don't have free rein over the space to buy everyone a 5 gallon (not that we'd have the room for them anyway) but my water gets changed every couple of days, and my fish are happy and healthy. I only wish I could afford the space for bigger tanks, because I'd like to decorate the tanks, which is almost impossible with 1 gals. >_<
Someday, we'll have more space, and bigger, more natural looking tanks!!
Bettas need 1000 gallon swimming pools to be happy. They live longer if they had a diving board. :)
Kidding aside, I share the same opinion that it is all betta specific on whether they will be happier in a big or small tank. I've seen it both ways. Just as long as the needed water changes are adhered to, regardless of tank size, then you're fine.
My girl HATES anything under five gallons, she will swim frantically around the tank and lay on the bottom. When she lived in the 2.5 gallon she would just circle her tank for an hour straight and try to swim past the the glass and once she realize there was no way out would just lay on the floor. In her 10 gallon she hasn't stopped exploring and hiding in her plants. I think a lot of it with betta in big tanks is thick plant coverage. Not even just plants here and there but i mean floor to top covered in greenery they can play in and caves they can explore. Can't wait to upgrade my boys to larger tanks, they will love it.
A one gallon is fine IF you can heat it and do water changes often. A betta will always be happier in a well planted and thought out larger tank though. And by the way, a bubble nest has nothing to do with happiness, it is simply a instinctive behavior. I have seen bettas in their shot glass store cups building bubble nests.
I think my main concern about 1 gallons is recommending them for young kids or absolute beginners with fish. In all honesty, if somebody told 14 year old me to change a bowl of water for a fish every day or even every other day, I would probably not do it, lmao.
Also the same reason mentioned before with heating it safely. I remember I had a heater that was recommended for 1-3 gallons of water. I put it in a 3 Gallon KK and it barely heat it to 80F...then I tested it in a 1 gallon and it went up to almost 90F... (luckily no fish was in there).
With large tanks the temperature and water chemistry are much more stable and definitely beginner friendly.
No matter what size tank you have you will need to make water changes-be it 1gal or 10gal-weekly to twice weekly to maintain water quality. IMO-what is important is teaching proper care and feeding to avoid water quality problems that can lead to fish problems.
As for heating, I have not found any issue with heating 1gal tanks by using the preset 78F type heaters in the many years I have kept Betta in 1gal tanks.
I try not to discourage new hobbyist by making it sound too complicated or that you need all kinds of expensive supplies or care that will take most of your time. This is a fun hobby for any age to enjoy. There are so many ways you can successfully keep this species-after all......