Okay so i've been basically cycling my 21 gallon with my betta and i'm a bit confused. I have to do water changes weekly but ammonia level hasn't started to raise yet but if i do water changes wouldn't that prevent ammonia to raise and start the cycle?
Are you testing the water with strips or a liquid test kit? 21g is pretty big for just 1 Betta, is there anything else in there? Weekly water changes are not going to hurt the cycle. I would've been happy to only have to do weekly water changes with my fish IN cycles, I was doing them about every 3 days. If you are showing any levels of ammonia or nitrites a water change is needed. If the nitrates go above 40 a water change is needed.
If you only have one Betta in that large a tank then it will be a while before ammonia levels get up. I would suggest adding a few more (compatible) fish to increase the ammonia load and help the tank cycle quicker. As long as you stay diligent with water changes then no harm can be done.
What was your end plan for the tank? We're you just going to have the Betta or had you planned on adding other fish? I personally have my males sharing their 10g tanks with 1 mystery snail each, my large tank is a sorority of 10 with a snail & 2 CAE's. I know that you don't want anything similar to the Betta, no long flowing fins or bright colors because there's usually issues.
I was planning to add other fishes with my betta. I love bettas but I don't like caring for just one fish that's why i bought something bigger than a 5 or 10 gallon!
and okay i think i might go to the petshop tomorrow or friday. Do you think black neon tetra could work?
I think like anything with a Betta its possible but there could be problems. Is your tank planted well with hiding spots? Is your Betta mild mannered? You'll just have to keep on everyone & have a back up plan in case it doesn't work. Make sure you get the right number & gender mix of tetras.
I think if you click on aquariums near my picture you'll see a picture of it but i basically have 2 live plants, 2 fake plants, 2 small caves in which the betta never goes and a bigger ornament that looks like a log. My betta chills in the log and on the fake plant most of the time. If he is mild mannered? I don't know but he flares a lot.
Bettas get along well with a lot of tropical schooling fish like tetras, danios, rasboras, cherry barbs, Julii Cories, Otocinclus catfish...
Just nothing with colorful, flowy fins; or anything else territorial like angelfish or rainbow sharks.