Betta fish need at least 5 gallons. Also, they're tropical fish so they need a heater that heats up to around 78 degrees (adjustable heaters are best). Make sure to get a filter too! They not only keep the tank clean, but are crucial for cycling the tank since a lot of the beneficial bacteria live in the filter media.
(Cycling is the process in which you get the bacteria that convert ammonia into a safer substance to grow in your tank so your fish doesn't get ammonia poisoning!)
Also, just a heads up, you only need to replace your filter media when it starts falling apart. Rinse gunk out by swooshing the cartridge around in tank water since the chlorine in tap water will kill the beneficial bacteria and can cause the tank's cycle to crash
I recommend this filter! It has an adjustable flow and it's pretty cheap
Bettas also appreciate a decent amount of plants and hidey holes :)
I have this Marina S10 Power Filter https://www.amazon.com/dp/B0032G8TPW?ref=ppx_pop_mob_ap_share on the back of a 20 long mostly for a little surface movement. It's silent if you remove the top. It's just a plastic lid that won't sit right. I put a bag of purigen and a couple of pieces of filter foam in there.
Get this filter and use a real sponge media instead of the lame cartridge. It´s 15 bucks on amazon.
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I keep three smallish filters going at all times on my 20-long. Rather than clean them when the tubes get gunky, I just move the sponges to a fresh machine. The ones I buy are good, but cheap enough ($12) to replace every nine months or so.
I have two that are 10-gallon, and one 20-gallon going at all times: https://www.amazon.com/Marina-A285-S10-Power-Filter/dp/B0032G8TPW/ref=sr\_1\_5?dchild=1&keywords=marina+power+filter&qid=1624410107&sr=8-5
Smaller than i thought. Hard to find hob filters for such a small tank. You can try Penn Plax cascade 20, though i saw its out of stock on amazon.
Also, i think this would be fine as well.
If it ends up being to much of a flow when pouring back into tank, you can just baffle it with a sponge.
I have this filter https://www.amazon.com/Marina-A285-S10-Power-Filter/dp/B0032G8TPW
I have one plant in there, I can't remember what it is I think it's an Amazon sword or something, I remember getting the recommend kind for my type of tank. I have no idea how many I need or what to do for them though.
Do you have a walmart by you? They sell empty 10 gallon tanks for 14.99 regularly priced. You could order from the website to store, too. https://www.walmart.com/browse/pets/10-gallon-aquariums/5440_202074_8218041
I like these cheap filters I got off of Amazon that have an adjustable flow. They're 13.99 each. https://www.amazon.com/Marina-A285-S10-Power-Filter/dp/B0032G8TPW/ref=sr_1_1?ie=UTF8&qid=1522288540&sr=8-1&keywords=marina+s10+filter
Then you'd only need one more heater, and if you keep the water level low enough in the 10 gallons you shouldn't have any issue with jumping until you can get hoods and lights, and even if you kept the water level really low it'd be way better than what they have now.
Link to the filter - less than $13.
https://www.amazon.com/gp/product/B0032G8TPW/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
I'd recommend this filter, it has an adjustable flow
https://www.amazon.com/Marina-A285-S10-Power-Filter/dp/B0032G8TPW
I have a Marina S10 Power Filter, and it's running great. I replaced the default filters with polyester fiber fill, too. Cheap, quiet, easy maintenance.
I use this one for my 5-gallon. Doing a 10-gallon filter in a 5-gallon tank is a good thing.
I'm debating between this one https://smile.amazon.com/dp/B0032G8TPW/ref=cm_sw_r_cp_apa_fabc_CNZ4PRY2WM26A3K5F3XE?_encoding=UTF8&psc=1
And this one https://smile.amazon.com/dp/B089XYRN9Z/ref=cm_sw_r_cp_apa_fabc_F3GZTA93Q901RJGVHEZ5?_encoding=UTF8&psc=1
I already have the marina one in another tank so I already have spare filter cartridges for it, but that second one has an even smaller footprint. Idk. I plan to do aquarium things on Saturday so I have time to think but at the same time I need to hurry up and decide 😅.
If you'd like a hob one, I think this one is good because the flow is adjustable:
https://www.amazon.com/dp/B0032G8TPW/ref=cm_sw_r_cp_apa_i_A1znFb7E6ZASJ
I personally use this canister filter and I really like it. You'd have to choose your intake and outflow though:
https://www.amazon.com/dp/B005DGHRU2/ref=cm_sw_r_cp_apa_i_v.znFbHK4NTE6
Pic of tank: https://imgur.com/DBmerHY
I left the outer black coating on and I'm glad I did - it makes the filter, heater, etc. much less noticeable.
I am currently in love with this Marina Slim 10 - it's three-stage, super quiet, and small. And $13.99.
I'm using Marina Slim S10 HOB filter on 3 gal half-moon tank, Azoo Mignon 60 (and another brand of the same filter) on 1gal and 2.5 gal long, and Tom internal filter in 1-1.5 gal cubes, with filter media cage removed and filter floss added to this micro pump, flow pointed upward.
Adding Matten filter to a shrimp tank (Poret foam, flow 2.5x tank volume/hr) is a good idea, additional grazing area. Do image search for this and you will see how it looks like. I have Azoo on one short side of the 2.5 gal long tank, and Matten filter on the opposite short side. This, a lot of java moss and feeding sustained more than 100 shrimplets until they grew and had to be moved elsewhere.
I've got a Marina Slim filter with 3 cartridges you are supposed to replace . I usually replace one every week. Should I just be rinsing it? It's not cheap.