I have a barrage of information for you... and plz don't take it as an attack, but many years of fish keeping advice (I also have 6 bettas, some of which are over 3yrs old atm):

You've been given a lot of misleading information. Keep in mind that fish stores are usually more interested in making a sale rather than giving you "the best" advice.

First off, you should consider moving your betta out of a 2.5 gal bowl without a filter and heater. Although you say your betta is very happy, 1 month is not a very long to have a betta. They can easily live 5+ years in proper tanks. In a bowl, Ammonia (fish waste) builds very very quickly and this is VERY toxic to fish. Bettas are hardy, but they are tropical fish and require the EXACT same amenities as any other tropical fish, besides the ability to breathe oxygen. Because bettas don't need aeration in a tank to survive, it is a common misconception that they do not need filtering or heating.... this is their own demise.

Without a filter in a tank that size, you would need to change 50% of the water every other day at the least to keep a healthy, thriving betta. Don't believe me? Buy and liquid ammonia water test kit and watch how high the ammonia rises in just a couple of days. I consider 2.5 gallons the bare minimum for a betta WITH a filter. 5 gallons is better to avoid filter current (as bettas become stressed with too much current).

A heater is a must in any tropical tank, including a betta tank... especially when you consider the temperature fluctuations of such a small enclosure. At night, the temps can drop almost 10 degrees F. Consider in a natural environment, the temperature of water would not even drop 1 degree F during night time. When you consider drafts, windows, and other variables, you have a tank with constantly fluctuating temps. This can eventually stress your betta and lower their immune system ---- therefore disease. A small, cheap heater will keep the temp at a constant 80 degrees F. This is easier in a 5 gal tank.

There is also the consideration that the more swimming room, the happier your betta will be. It is more enjoyable for the owner to watch your betta zoom all over a larger tank and SWIM like a fish.

"This bowl was set up a month ago, the fish moved in 4 days later and I just did a %10 (2 litre) water change last week."
Setting up a non-filtered bowl for 1 month does absolutely nothing.... even a filtered 3000000 Gallon tank setup for a month without ammonia supplementation does not do anything. As stated earlier, that sort of water changing schedule is not nearly enough.

Feeding: bettas should be fed 3-4 PELLETS twice a day. Tried and true among betta experts. The "low maintenance every couple of times a week" spiel is a load of bull.

That's all I will say for betta fish care.

As far as plants, I'm not an "aquatic plant guru" but have some experience. What you are describing on the root system of the Sword is most likely a bacteria based 'algae' present in high Ammonia conditions (BAD). Amazon Swords should do quite well in low light tanks (I have mannnny).

As far as keeping your betta bowl in direct sunlight, that is ill advised (for any tank). Algae blooms very quickly in direct sunlight and it is common practice to keep tanks away from windows and sunlight for this reason.

Algae does not harm fish, but excessive algae is a sign of a tank that is not cared for vary well, as it absorbs harmful chemicals. The more harmful chemicals present, the more algae flourishes.... so it does remove this, but think of it as no-win situation.

My appologies, I'm unfamiliar with the "African Fern", so no advice there.

Earthworms = great food chopped into small pieces.

visit fishforums.net and check out the betta section. Loads of reliable advice. Loads of good info on bettas and advanced techniques. Hell, even post up an introduction topic in the betta section and ask for advice (you're welcome to mention my name if you are skeptical about the advice I have given here). I'm more of a fish expert than a "green thumb" ;). here is a direct link to the section: http://www.fishforums.net/index.php?s=4ceeffdbdd3d9c348bbd8f1da327eedc&showforum=5

Best of luck!

BTW what have you named your betta?

Hi
I moved my 150 gallon tank out to the shadehouse into dappled sunlight . Had often heard the rumor about algae and direct sunlight. Has actually worked out just the opposite . Best planted tank I've ever setup. had a lot more algae indoors but not a fair comparison as it was SW.
For a small tank I'd be concerned about heat gain though. gary

I agree about keeping a betta in a small bowl, and why it will die on you soon if you don't water change daily.

If you want a small tank that will allow you to change only weekly, for a single betta, an Eclipse System 3 would do. It still wouldn't give your fish as much room to swim as it really needs, but would keep it healthy, in about the easiest tank to maintain as is available.

Or, and better, a 5 or 6 gal. version. Just get it out of that silly bowl ASAP.

Meanwhile, get a 1 gal. jug and every night, fill it, add whatever conditioner you need for your water and let it sit overnight near the fishbowl, so it will rise or lower to the same temp. as the bowl. Then, every morning, do a 1 gal. water change. That will keep your fish alive until you can set up a proper home for it.

But just think about how it must feel to have your lungs burnt with ammonia and perhaps you will better understand why it kills fish, including betta. The water may look clear, but it's slowly burning away the delicate inner lining of that poor fish's gills.

BTW: In the wild, betta DO NOT live in cup sized indentations in the ground. They live in large ponds and paddies communially until the breeding season, then set up territories within them. The fighting instinct of the males is triggered by too close proximity. Coupled with selective breeding for aggressive behavor, the result is the so-called Fighting Fish, but give even them enough space in a larger tank, and they will establish their own territories and absent a female, will generally leave each other alone.

I had had Betas for a long time. Now have moved to another state and starting over. I bought a Beta a few weeks ago and bought what was supposed to be a 3 gallon tank, which in turn turned into a 2!/2 gallon. My fish is beautiful, I named him Kringle because it was around Christmas I got him. Now my question is, When I lived up north I had my Betas in a 3 gallon cube and they did very well, I always use live plants, heater, filter etc. Kringle seems to be doing fine. His tank has LED lighting and he is in a darker place in my living room. I do have filter and heater for him I do feed him 2x a day and turn off the light around 7pm, on around 7:30 am. I change around 50% of his water once a week. I also wipe down the inside of his tank. Now I am seeing algae starting to grow on the plant and the rocks plus some on the sides of the tank. Is this a natural affect? My tanks up north had this too and never seemed to bother the fish. I only had 1 tank with a Beta that never has this but his buddy was a cat fish. Should all fish tanks have some sort of algae eaters in them? Do they all get this? When I had my tanks up north this didn't seem to bother me or the fish but here in Fla with this water that is recycled I have been very careful. I do use Prime as a conditioner. The plant is a low light sward but it seems to be dying off. New state, new fish care. Can any one give me any ideas of what to expect? I would love to get more Betas when we move to a permanent home. Thanks all

Fish bowls are not goid I have mine in a 10 gallon community tank the larger the tank the more room for the betta I recommend a 5 or six gallon tank with a filter and if alge is a problem the tank would be big enough to add a pletco now under stand pletco can get BIG so get a small one some pets stores let you change them for a smaller one when they get to big even with a 5 gallon tank changing the water about once a week would be recommend as for the millipeds though they are over all harmless their shell is hard to get through and would exhaust your betta just trying to get to the meat also depending on your area millipeds can Carrie dieseaes so I don't recommend especially if you put out bug spray or other pestisds around your house and in your

Guess I'm doing something right. It is now 2019 and I have 13 tanks set up, 2 20 gal, 4 10 gal 4 5 gal. 3 3 gal. All fish doing very well Bettas and Teteras not in the same tank except for my 20 gal long. What a difference a few years make. I do have a beautiful Bumble Bee Betta in a community tank with Danios, Teteras, White clouds and cat fish plus a 2 Placo and Mystery snails. All are well and happy. Not over stocked and change about 35% water every other week. Trial and erra is the key to this hobby. Common seance too. Going to set up a 6 gal tank for a rude boy betta today I had to pull out of my 20T tetera tank. He's now in a 3 gal but loves to swim. So peaceful, my living room is a living, breathing room. Ya all have good luck with what ever you do. Just keep the lights on around 7hr and all should be well